浙江大学《植物生理学》课程期末考试试卷(A)

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植物生理学考评方式与标准

本课程期未闭卷考试占50%,着重考核基本概念、基本理论的掌握及运用能力；实验成绩占30%，重点考核动手能力和实验结果的分析能力和深度；平时成绩占30%，由作业成绩、演讲成绩、提问和讨论等组成。期未考试由试题库统一抽取。

要求每届学生的最终成绩呈正态分布，上课班级学生平均分数在75分。部分期末考试试卷及参如下：

浙江大学2007–2008学年秋冬学期

《植物生理学》课程期末考试试卷(A)

开课学院：生命科学学院，考试形式：闭卷，允许带答题用笔入场考试时间：2008年1月22日14：00-16：00, 所需时间：120分钟考生姓名：学号：专业：题序得分评卷人

一二三1，2 三3，4 三5，6 三7 三8（9）总分一、. Translate the following terms in Chinese or explain them in English (Total 20 marks, 0.5 mark for each)

1. Bound water ：束缚水 2. Guttation：吐水

3. Temporary wilting：暂时萎焉 4. Stomatal transpiration：气孔蒸腾

5. Stomatal conductance：气孔导度 6. Transpiration efficiency：蒸腾效率 7. Transpiration-cohesion-tension theory：蒸腾拉力-内聚力-张力学说 8. Greenhouse effect：温室效应 9. Photosynthetic membrane：光合膜 10. Primary reaction：原初反应 11. Light-harvesting pigment：捕光色素

12. Photosynthetic unit：光合单位 13. Emerson enhancement effect：爱默生双光增益效应 14. Photosynthetic chain：光合链 15. PQ shutter：PQ穿梭

16. Cyclic electron transport：循环式电子传递 17. Assimilatory power：同化力 18. Photoinhibition：光抑制 19. Anaerobic respiration：无氧呼吸 20. Terminal oxidase：末端氧化酶 21. Macronutrients:大量元素 21. Rhizosphere：根际、根围 22. Solution culture：溶液培养 23. Antagonism：拮抗作用 24. Synergism：协同作用 25. Allocation：配置，参入 26. Metabolic source：代谢源

27. Phloem transport：韧皮部运输 28. Differentiation：分化 29. Dormancy：休眠 30. Growth kinetics：生长动力学（曲线） 31. Gibberellin：赤霉烷 33. Plant growth retardant：植物生长延缓剂 34. Juvenility：幼年期 35. Phytochrome：光敏素

36. Reaction oxygen：活性氧 37. Deciduous senescence：脱落衰老 38. Abscission：脱落 39. Abiotic stress 非生物胁迫 40. Chilling injury：冷害

2．Definitions (Choose 8 of 10 followings, total 24 marks, 3marks for each)

1. Water potential: Water potential is defined as the difference in free energy per unit volume, between matrically -bound, pressurized, or osmotically- constrained water and pure water.It is expressed as following formula: Ψw=Δμw／Vw. Ψw reflects the capacity for chemical reaction and movement in plant system.

2. Symplast: symplast is the highly ordered, three-dimensional, connected network of living protoplasm and plasmadesama. It is an important pathway for free translocation of water and low molecular solutes.

3. C4 photosynthetic pathway: C4 pathway is one of photosynthetic pathway, in which the initial product of CO2 fixation is OAA, a C4 dicarboxylic acid. It also called Hatch-Slack pathway consist of CO2 fixation, C4 dicarboxylic acid location and PEP regeneration.

4. Photorespiration: a process, which carry out only under light, uptakes of O2 and releases of CO2.

5. Light saturation point: It is the light intensity at which Pn reaches maximum even continue increase in light, Pn increase no longer.

6. Respiratory quotient: Also called respiratory coefficient, it referred as the ratio of moles (or volumes) of released CO2 to absorbed O2 by plant tissue at the same time.

7. Critical period of nutrition：A period during which plant is most sensitive to nutrition

deficiency and is most easily injured by this, but the nutrition requirement is not always largest at that period.

8. Growth center：Growth center is a part of plant body, which grows fastest and takes up most of assimilate or inorganic nutrition, such as shoot apices during vegetative stage and fruits during fruit-setting.

9. Plant hormone:Plant hormone is naturally occurring organic substance that can be transported from the synthetic tissue to a specific target tissue where, at low concentration, exert a profound influence on physiological process.

10. Photoperiod induction:Plants can flower in both suitable and unsuitable photoperiod conditions if it has got enough days of suitable photoperiod. This process is called photoperiod induction.

3．Questions（Total 56 marks. 1-7 are necessary to answer and choose

one between 8 and 9）

1. Why should we not apply a large number of fertilizers to plant in one time? (5 marks)

If we apply a large number of fertilizer to plant in one time，the solute concentration of soil will be higher than that of plant tissue. The water potential in root exceeds that in soil and prevent root from water absorption. Consequently, plant will suffer from wilting, even die.

2. Briefly describe the factors affecting nutrients uptake by plant roots (5 marks) (1) Intrinsic factors such as ion diameter and valence affect nutrients uptake by plant roots. Usually small one and lower valence are easily absorbed by root. (2) Environmental factors such as light, temperature, water status, O2, pH, ion concentration and interactions between nutrients affects nutrients uptake by plant roots. The suitable light, temperature, and soil water and O2, and middle pH are favor of uptake. Synergism enhances ion uptake each other such as NO3- and K+, N and P etc. However, antagonism inhibits ion uptake each other such as K+ and NH4+.

3. What are the mineral nutrients with deficient symptoms appearing on older leaves or younger leaves? Describe the most typical symptoms of one of them for each class (5 marks)

There are elements N,P,K,Mg,Zn and Cl. Their symptoms appear first on older leaves There are elements S,Ca,Fe ,Mn,B,Cu and Mo etc. Their symptoms appear first on younger leaves.

The most typical symptom of N deficiency is old leaf chlorosis. And the most typical symptom of Ca deficiency is growth apical rotting.

4. How does plant control the growth of stem apices at the level of gene expression? (5 marks)

The growth of stem apices requires increase in stem cell numbers which is controlled by WUS expression. When higher WUS expresses, Stem cell number increase and stem apices grows fast. When the stem cell numbers increase, they enhance CLV3 higher expression, which combines with CLV1 protein inhibits WUS expression. Therefore stem cell numbers decrease, stem apices grows slowly, which makes CLV3 lower express and WUS higher express. A new cycle begins. This feedback of gene by gene controls the growth of stem apices at the level of genes. 5. What factors determine whether the product of the PCR cycle will be

converted to starch in the chloroplast or sucrose in the cytosol? (5 marks) There are 4 factors triose-P in chloroplast, orthophosphate and sucrose in cytosol, and F-2,6-P concentration in cytosol, directly determining the product of the PCR cycle will be converted to starch in the chloroplast or sucrose in the cytosol. Higher concentrations of triose-P in chloroplast and sucrose in the cytosol and lower

concentration of orthophosphate in the cytosol will result in accumulate starch in the chloroplast because of feedback inhibition by limited transport out of triose-P from chloroplast. Higher concentrations of orthophosphate and lower concentration of sucrose in the cytosol will make the product of the PCR cycle convert to sucrose in the cytosol because sucrose can be exported out from source leaf to sink organs and

enough orthophosphate can be used for exchange of triose-P in chloroplast with

orthophosphate in cytosol. Lower F-2,6-P concentration in cytosol is favor of sucrose synthesis in cytosol.

6. How to delay fruit senescence and to store it longer? (8 marks)

Fruits can be divided into two sorts: one called respiratory-climacteric fruit such as banana, apply, strawberry etc and the other called non-respiratory-climacteric fruit such as orange, watermelon etc. For different sorts of fruits, different kinds of method should be applied to store them so as to delay their senescence.

As to the first type, we should stick to a general principle: decrease Rd, and delay the climacteric. They should be stored in those conditions:(1) low temperature, but not below 0℃ avoiding chilling or freezing injury;(2) gas control, higher CO2 below 4% and lower O2, but not inducing anaerobic respiration, and guaranteeing suitable ventilation;(3) removing Eth whether the fruit are in storage or transportation;(4) gene modification, creating transgenic plant that is not active to ACC or form Eth.

As to the second type, like the first type, we should control the storage condition too. Such as relatively low temperature, higher rate of CO2, lower rate of O2, and suitable ventilation so that Eth will not cumulate.

Beside those above, we also apply the some methods for delaying fruit senescence, such spraying calcium solution and other flash-keeping membranes before the picking and during the transportation, respectively, and store the fruit by fast freezing.

7. How to regulate the ratio of root to shoot? Give an example and explain why it

is (8 marks).

Root-shoot ratio as an index for the coordinative between root and shoot is referred to dry root weight dividing dry shoot weight. Regulation of the ratio means increase the ratio or decrease the ratio.

When we plant leaf vegetable, we should decrease the ratio by enhancing leaf growth or inhibiting root growth. Application of nitrogen in the soil or culture solution often results in the lower ratio because higher nitrogen can compose the photoassimilate to synthesize proteins in leaf. Those proteins promote leaf growth. The root will grow slowly because it gets less photoassimilate form the shoot on the one hand. Too much nitrogen may inhibit root growth too.

When we culture plant for root tubers, we should increase the ratio by enhancing the tuber growth but not inhibiting leaf growth so much. Application of phosphorus and potassium, which mainly improve photoassimilate transportation out of the leaf, importation into the root and accumulation of starch in the root, usually increases the ratio.

* Students can also use other regulations if they are useful and explain why those increase or decrease.

8. What should we do for delaying plant senescence? (15 marks)

Senescence is a program in which the function of organ or whole plant naturally declines to death. This is an essential phase of the growth and development in plant. Both internal and environmental factors cause plant senescence. Therefore, we should do it in several aspects.

First, we should use germplasms resistant to senescence by selection of varieties

and cultivars resist to senescence because most plants have their resistant variety or cultivar we can use.

Second, modern technology have provided us a tool for senescence-delayed transgenes and produced some stay-green plants such as tobacco, sorghum, soybean and rice etc. We can continue to improve them for delaying senescence.

Third, Application of plant substances for resistance to senescence is also available such as utilization of CTKs，BRs，polyamines，IAAs for different plants.

Fourth, it is necessary to provide good conditions for plants when we culture them. The plants require sufficiency water, oxygen, mineral nutrition, suitable light irradiance and temperature, and non biotic or abiotic stresses.

9. Describe the effects of temperature on plant growth and development？(15 Marks)

Plant growth and developments are based on metabolism, most of which are catalyzed by enzymes whose activities largely depends on temperature. Therefore, temperature is one of the most important environmental conditions for plant growth and development. High or low temperature is disadvantageous to absorption, transportation and utilization of water and mineral nutrition by plant, results in growth inhibition even death because of the physiological drought and nutrition deficiency. High or low temperature causes declination of photosynthetic rate and increase of photo-and dark-respiration, especially anaerobic respiration, which often result in starvation to death or growth stunt because they damage the structures of chloroplasts and mitochondria and decrease in photosynthetic and oxidative phosphorylation, and enzymes’ activities for those procedures. High or low temperature stress often cause heating or chilling injury and make cell autolysis owing to lipid liquefaction and phase change of biomembrane, loss of metabolism compartmentation and declination of energy charge. High or low temperature results in lower synthesis of organic substance including nuclear acids, proteins and lipids and make plant hormone metabolism change, usually decrease in IAA and CTK but increase in ABA etc to inhibit plant growth and to accelerate plant senescence. Temperature directly influences plant flowering and setting, for instance, some plants require low temperature for vernlization and they can not flower under high temperature condition and lower temperature lead plants favor temperature not setting as pollen germination and pollen tuber elongation are inhibited.

Therefore, optimum temperature is an essential prerequisite to plant growth and development.

浙江大学2007–2008学年春夏学期

《植物生理学》课程期末考试试卷(A，答案)

开课学院：生命科学学院，考试形式：闭卷，允许带答题用笔入场考试时间：2008年6月26日8：00-10：00, 所需时间：120分钟

考生姓名：学号：专业：

题序得分评卷人

一二三1 三2 三3 三4 三5 三6(7) 三8(9）总分一、Translate the following terms in Chinese or explain them in English (Total 20 marks, 0.5 mark for each)

1. Aquaporin:水孔蛋白或水通道蛋白 2. Root pressure：根压 3. Active uptake 主动吸收 4. Transpiration：蒸腾作用

5. Stomatal resistance：气孔阴力 6. Plasmolysis：质壁分离 7. Solute potential：溶质势 8. Chloroplast：叶绿体 9. Thylakoid：类囊体 10. Envelope：被膜

11. Stroma：（叶绿体）间质温表 12. Photoassimilate：光合产物（同化物） 13. Carotenoids：类胡萝卜素 14. Xanthophyll：叶黄素 15. Fluorescence：荧光 16. Etiolation 黄化

17. Photophosphorylation：光合磷酸化 18. Aerobic respiration：有氧呼吸 19. Glycolysis：糖酵解 20. Mitochondria：线粒体

21. Essential elements：必须元素 22. Hydrophyte：水生植物 23. Hydroponics：水培（溶液培养） 24. Chlorosis：失绿发黄 25. Synthase：合酶 26. Partition：分配

27. Metabolic sink：代谢库 28. Transfer cell：转运（移）细胞 29. Development：发育 30. Apical Dominant：顶端优势

31. Cell mitotic stage：细胞分生期 32. Brassinolide：油菜素内酯

33. Plant growth inhibitor：植物生长抑制剂 34. Vernalization：春化作用 35. Florigen：成花素 36. Critical daylength: 临界日长

37. Overall senescence：整体衰老 38. Programmed cell death：程序性细胞死亡 39. Halophyte：盐生植物 40. Moisture injury：湿害

41. Hydrogen bond 氢键 42. Beneficial element 有益元素 43. Ion channel theory离子通道通道学说 44. Tolerance耐性

45. Assimilate power同化力 46. Photochrome光敏素 47. Differentiation分化 48. Microtubule微管

二．Definitions (Choose 8 of 10 followings, total 24 marks, 3marks for each)

1. Water requirement: Water requirement is a reciprocal of transpiration efficiency, meaning that plant consumes water quantity (g) for making 1g of dry matter.

2. Guttation: When soil has enough water and atmosphere is warm and higher RH, often in the

early morming, unwounded leaf can secret sap form the tip or margin of leaf through

specialized pores, or hydathodes.

3. Physiologically acid salts: Physiologically acid salts are defined as the salts can result in

solution acidification, as uptake of cation by plant is larger than that of anion, such as NH4Cl、NH4SO4、KCl、CaCl etc.

4. Quantum efficiency：The plant assimilates number of CO2 by absorption of 1 molecule of quantum.

5. Light compensation point:The light intensity at which Pn is zero.

6. Alternative oxidase: The respiration is not blocked by normal respiratory inhibitors, such as CN—, N3— (azide) or CO. Terminal oxidase involed in this respiration pathway is alternative oxidase, insensitive to cyanide.

7. Polar transport: It is specific transport for plant hormone IAA, that can only be transported

form morphological top to bottom.

8. Grand period of growth:The growth of tissues, organs and even a whole plant exhibit a typical model with slower-faster –slower in life cycle. The total growth appears S-shape growth curve---logistic curve and the growth rate is a parabola. 9. Photoperiodism: The response of plant flower (development) to photoperiod (day length of 24 h cycle).

10. Adaptation: Adaptation is permanent resistance to stress in morphology and structure, physiology and biochemistry under long-term stress condition.

三、Questions（Total 56 marks. 1-7 are necessary to answer and choose one between 8 and 9）

1. Why should we keep a bulk of soil of root and cut off most of leaves when transplant a big tree? (5 marks)

Root hair is the main organ for absorption of water from the soil. When we transplant a big tree, most of the root branch and root hairs have been removed or damaged. It is necessary to keep a bulk of soil for protection of roots from further damaging the root hairs by which plant can absorb some water to meet water

equilibrium. Meanwhile we cut off most of leaves in order to decrease leaf area for loss of less water by transpiration. Therefore, the plants can catch with water equilibrium and survive after transplanting.

2. Describe main symptoms of N deficiency in plant (5 marks).

The most typical symptom of N deficiency is old leaf chlorosis. The plant became yellowish, stun and radish in the stem base. The plant has few branches or tillerings and poor setting percentage or few and small fruit. The root appears less, thinner and longer.

3. Why can we say that Rubisco is a key enzyme for photosynthesis (5)?

Rubisco is only an enzyme catalyzing the inorganic CO2 into sugar in large scale on the earth. It has functions in both photosynthesis and photorespiration. As a carboxylase, it catalyzes the reaction, in which CO2 combines with ribulose bisphosphate (RuBP) to form two molecules of 3-phosphoglycerate (3-PGA). 3--PGA can continue to reaction till photosynthetic carbon cycle finishes. As a oxygenase, it catalyzes the reaction, in which O2 combines with RuBP to form 3-PGA and glycolic acid-2-phosphate. The latter can continues to reaction till photorespiration (C2

cycle) finishes. Therefore, Rubisco is a key enzyme for photosynthesis.

4. How to store dry food and seed longer? (7 marks)

High respiratory rates of the dry seed will consume more stored organic nutrition of them. Therefore it is most important for them to reduce the respiratory rate during the storage periods. The respiratory rate can be greatly impaired by microorganism, environmental conditions in dry food and seed. If you want to store them longer, following things should be done.

When keep the seed and food longer, you fully dry the seeds and control the seed water content below safety water content, in which seed can be stored one cycle year or do seed-ultradried storage ; you can lower food temperature to -4 ~4 ℃, even super-low temperature storage（-193℃）; And you regulate gas components by filling with N2, CO2 or autonomously decrease in O2 by respiration as well as you use the chemicals to kill the microbe or insects.

5. Describe the relationship between plant hormone and flower (7 marks).

Most of plant hormones can influence plant flower formation. GA and Eth are well known plant hormones which regulate flowering. GA can promoting bolting and flowering instead of low temperature and long daytime and enhance male flower initiation of cucumber but female flower initiation in a lot of tree. Eth can promote male flower initiation of many kinds of plants, especially for cucumber, pumpkin etc. IAA also enhances male flower initiation and flowering due to induction of Eth.

6. Describe the relationship between source and sink? (8 marks)

Source or metabolic source, referred as the organs or tissues which produce or/and transports out assimilate ,such as developed leaf，root tuber or tuber during germination. Sink or metabolic，referred as the organs or/and tissues which consume or/and store assimilate, such as root，seed, fruit, root tuber and tuber during developing.

The relationship between source and sink show the followings: (1) variable. For instance, the young leaf is sink, half-developed leaf is both sink and source and well developed leaf is source.(2) promotion and inhibition by each other, a small source must result a small sink，and small sink also inhibits source activity. But too strong source makes sink low activity because the source uses much assimilate itself and apply the sink less assimilate. Too strong sink results in premature of source because it attract much more assimilate from source and inhibits source growth and development.

7. Describe what types of gene mutation result in apetala 2-2, apetala 3-1 and

aganous 1 of the following figure, respectively, based on the developmental model of 4 floral whorls. (8 marks)

The developmental model of 4 floral whorls indicates that sepal, petal, stamen and carpel of flower morphology are controlled by 3 types of genes called A, B and C

respectively. Each gene type controls two adjacent floral whorls development. A type regulates sepal and petal development, B controls petal and stamen development and C controls stamen and carpel development. From the figure we can deduce that apetala 2-2 is A type mutant due to loss of sepal and petal, apetala 3-1 is P type mutant due to loss of petal and stamen and aganous 1 is C type mutant due to loss of stamen and carpel.

8. Describe physiological and biochemical changes during senescence (15 marks).

Senescence is a program in which the function of organ or whole plant naturally declines to death.

This is an essential phase of the growth and development in plant。Lots of things happen during senescence.

A. SAGs expression. Senescence is controlled by special genes called senescence-associated

genes（SAGs）,people have recognized the increasing expression of senescence-upward genes，most of genes code enzymes for hydrolase, such as DNase, RNase, Protease, phospholipase。

B. Degradation of biomacromolecules.(1).DNA degrades，RNA changes in quality and quantity.

(2)Protein synthesis decreases and its degradation increases. For instance, soluble

protein-----Rubisco decreases by 85%, thylakoid membrane protein decreases by 50%in the last stage。

C. Disorder of plant growth substance.CTK content decreases and Eth,ABA,and JA et al increase. D.Equilibrium loss of Ca2+ between intro- and extra-cell. Increases in Ca2+ of cell results in the huge change in motabolism.

E. Free radicals burst and the decline in the capacities of scavenger systems. Inorganic free

—。。。。

redicals（O2、1O2 and OH）and Organic free redicals: (ROO、RO) rise and •Non-

protective enzyme system —antioxidant: (Cytf、glutathione、ascorbic acid、ubiquinone, vitamin E and carotenoids) and Protective enzyme systems (SOD、AAO、 glutathione reductase、 catalase and glutathione peroxidase) are down-regulated.

9. How to improve photosynthetic productivity in physiology and production (15 marks)?

In physiology, photosynthetic productivity is not high enough because of those reasons: (1) Lower net photosynthetic rate (Pn) of single leaf.

(2)Lower Pn of plant canopy (populations), resulting in much leakage of sunlight, higher

transmittance or/and reflectance of light by leaf, and light-saturation for carbon fixation. (3) No enough accumulation of assimilate in products.

Therefore, increase in photosynthetic productivity can be considered as followings:

(1) Increase in Pn of leaf includes higher ability of light absorption, transfer under lower light

condition, such as higher photo-electron transport and photophosphorylation, less photoinhibition under higher light condition, and higher activity of enzymes for carbon fixation (especial Rubisco and its activase) etc by selection of higher Pn varieties and some transgene plants.

(2) Increase in Pn of plant canopy includes increase in leaf area by a suitable planting density, and

good application of fertilizer and utilization of erect plant type, extending of photosynthetic time by enhancing planting system, such as increase in multiple crop index, intercroping and using variety with longer growth period, and decrease in photorespiration and respiration by selection of higher Pn varieties and some transgene plants.

(3) Increase in accumulation of assimilate in productive organ includes promotion of harvest index

by using better variety, good conditions for setting, such as application of mineral nutrition, light, CO2, water and temperature etc.

浙江大学2008–2009学年秋冬学期

《植物生理学及实验》课程期末考试试卷(A)

开课学院：生命科学学院，考试形式：闭卷，允许带答题用笔入场考试时间：2009年1月8日8：00-10：00, 所需时间：120分钟考生姓名：学号：专业：

一、 Choice (Select the best one of the following four answers, total 10 marks, 1 mark for each) 1. Plant tissue will （1） when it is put into a hypotonic solution.

(1) take up water (2) loss water

(3) get water equilibrium (4) occur all above

2. Permanent wilting is mainly resulted from （2） .

(1) the transpiration rate higher than water uptake rate (2) no available soil water (3) the higher respiratory rate (4) too high relative humidity

3. The transmembrane transport of NH4+ or NO3- mainly depends on （2） . (1) ion passive transport, (2) ion active transport (3) ion free diffusion (4) ion concentration gradient

4. In the following salt groups, （1） belong to physiologically acid salt.

(1) NH4Cl，K2SO4 and (NH4)2SO4 (2) NH4Cl，K2SO4 and NH4HCO3 (3) NH4Cl，K2SO4 and NH4NO3 (4) KNO3，Ca NO3 and CaHPO4 5. The receptor for CO2 fixation in mesophyll cell of C4 plant is （1） . （1） PEP （2） PGA （3） Ru5P （4） RuBP 6. Increase in light intensity will （1） in CO2 compensation point when the light intensity is below the saturation point.

(1) decrease (2) increase (3) be equal (4) all happen 7. P/O ratio for cyanide-resistant respiration is （3） (1) 3 (2) 2 (3) 1 (4) 1.5

8. The left leaves of plant will （2） in net photosynthetic rate if some leaves are removed from plant.

(1) decrease (2) increase (3) be equal (4) all happen

9. As we know, some plant hormones play a significant role on delaying leaf senescence, especially for （4） . (1) IAA (2) GA (3) ABA (4) CTK

10. The following events, （3） is differentiation.

(1) Seed germination (2) stem elongation (3) root hair formation (4) fruit swollen

二、Cloze (Fill the blank with suitable word(s) or phase(s), total 16 marks, 1 mark for each) 1. Heat injury often directly results in protein denaturation and lipid liquefaction. 2. The part of plant sensitive to vernalization is stem apical , while the part response to photoperiodism is leaf .

3. Higher root/shoot ratio of plant can be controlled by the means, such as paddy soil (field) drying , application more P,K fertilizer, and tilling or breaking root .

4. The balance of plant hormone IAA , genes WUS and CLV3 are necessary to maintain the shoot apical meristem activity,

5. In phloem sieve tubers undertake a long distance transport of photoassimilate and companion cells play an important role in phloem loading and unloading. 6. The methods for improvement of light energy utilization efficiency are:

promotion of photosynthetic rate, leaf area in unit, extending photosynthetic duration, and decreasing in photorespiration and respiration etc. 三．Definitions (Choose 8 of 10 followings, total 24 marks, 3marks for each)

1. Water potential (Ψw): Water potential is defined as the difference in free energy per unit volume, between matrically -bound, pressurized, or osmotically- constrained water and pure water.Ψw reflects the capacity for chemical reaction and movement in plant system.

2. Transpiration efficiency: A reciprocal of transpiration transpiration coefficient means plant produces quantity (g) of dry mater when it consumes 1kg of water by transpiration.

3. Reaction center pigments: There are kinds of specifically arranged chlorophyll a in reaction center, which can absorb light energy (or accept the energy transferred from the antenna pigment) and then convert the light energy into electric energy.

4. PQ shutter: A process in which H+ is pumped into thylakoid lumen from stromal side, then increases in pH in the stroma, while photosynthetic electron is transported in photosynthetic chain.

5. Essential elements: The elements in brief are necessary for plants to grow and develop. They include macroelements, C, O, H N, P, K, Ca, Mg, S, and microelements, Fe, Mn, B, Zn, Cu, Mo, Cl, Zi.

6. Temperature coefficient (Q10): it is an index to measure the effect of temperature on respiratory rate, which means the ratio of the respiratory rate at T plus 10℃ to the respiratory rate at T℃ as following equation: Q10= Respiratory rate at (t+10℃)/ Respiratory rate at t℃.

7. Allocation: Carbon allocation is referred the appropriation of carbon fixed by the photosynthetic carbon reduction (PCR) cycle into either starch or sucrose biosynthesis.

8. Growth inhibitors: A kind of Compounds which are resistant to IAAs in function and inhibit the growth of the apical meristem. The inhibitory effect can be reversed by IAA, but not by GA.

9. Differentiation: Differentiation refers to qualitative changes or differences other than size occur in anatomical characteristics and functions of cell, such as shoot apical meristem

initiates leaf formation.

10. Avoidance: Avoidance is a manner to avoid facing with stress using neither metabolic process nor energy. Such as very short-lifecycle plants in desert can availably avoid drought stress.

四、Questions（Total 50 marks. 1-5 are necessary to answer, Choose one between 6 and 7）

1. Why may we say that C3 pathway is fundamental pathway for plant kingdom? (5 marks)

C3 pathway is a photosynthetic pathway, in which the initial product of CO2 fixation is C3 compound (PGA, phosphoglyceralate). Not only it is only a way to fix CO2 to carbonhydrate in plan kingdom but also all photosynthetic pathway plants process that pathway.

2. Describe main symptoms of P deficiency in plant. (5 marks)

P deficiency results in extremely stun，young leaves appear dark-green in color and older leaves and base of stem exhibit vinicolor, plant have less tillers, grain and fruit, poor root development.

3. Compare the similarity and difference between respiration and photorespiration (7 marks)?

Similarity Difference in conditions, substrates in metabolic locations and pathways

Both uptake of O2 and release of CO2 Respiration

Both in light and dark, main sugar

Cytosol and mitochondrion, main pathway including glycolysis-citrate cycle and respiratory electron transport and phosporylation.

(1)Provide the energy (36ATP) for life activity.

(2)Provide the intermediate products (skeleton) for other biosynthesis, such as keto acid and NAD(P)H.

Photorespiration Only in light, glycolate Chloroplast, peroxisome and mitochondrion, main pathway including glycolate formation, oxidation, decarboxylation and deamination.

(1)Protection of photosynthetic apparatus from damage by high intensity of light

(2)avoiding inhibition of O2 to photosynthetic carbon assimilates

(3)limiting glycolic acid toxication and amend partial amino acid (Ser and Gly).

in functions

4. How does chilling injury damage the plants in physiology? (8marks)

Chilling injury in tropical or subtropical plants is caused by temperature above 0℃ (freezing point ), which could be broadly divided into two steps.

The first step is the change in lipid states. The biomembrane states became solid gel states from liquid crystalline state, resulting biomembrane leakage, loss of ion equilibrium and disorder in energy and substance metabolism.

The second step causes metabolic disorders of the plant, including that uptake function of roots declines and water balance losses. The physiological drought occurs because water loss by transpiration is more than water absorption by root system. Photosynthetic rate lowers, aerobic respiration decreases while anaerobic respiration increases, which make plant face to starvation. Organic substance degrades due to higher activities of hydrolase such as RNase, Protease etc.

5. What should be controlled in greenhouse to make plant growth better? (10 marks)

The plant is affected by lots of environmental conditions such as light intensity, temperature, soil moisture, nutrition concentration and abiotic stresses etc.

In greenhouse we should provide the plants sufficient light intensity and light quality by covering with transparent material which can even pass through a part of UV in order to photosynthesize and prevent the plant overgrowth. We should control the temperature to about growth suboptimum and the larger difference in temperature between day and night (about 10 ℃ higher in daytime than at night ) and ventilate in order to provide enough CO2 in the facility. We should keep the soil or substrate moisture neither too wet nor too dry and provide enough all essential elements to plant. If the plants are cultured with hydroponics, it is necessary to use flow culture or airing. If the plants are cultured in the soil directly, it is necessary to prevent soil from salty. We should shower the soil for other several seasons to avoid salt stress.

We should carefully deal with pests or pathogens by using pesticides which can kill them but safe to human beings. Sometime we should breed special insects to help plant pollination and use plant hormone for promotion of setting.

6. Describe the effects of light on plant growth and development. (15 marks)

The effects of light on plant growth and development are two aspects: In a certain quality and quantity of light is advantage to plant growth and development while over it is harmful for plant growth and development.

First photosynthesis is most important to plant growth and development. Light influences photosynthesis by enhancing chloroplast development and chlorophyll synthesis, providing energy to drive water oxidation, oxygen evolution, photosynthetic electron transport and photophosphorylation as well enzyme activation. Therefore photosynthesis only can carry out in light condition. However, superfluous sun light aggravates in

photoinhibition and photorespiration. Those result in declination of photosynthesis.

Second light influences plant photomorphogenesis and plant develops etiolation in dark. Photoperiod induces plant flower formation, and long day plants flower in longer daytime with shooter nighttime and shoot day plant flower just in opposite photoperiod. Light also influences lot of physiological events by phytochrome, such as seed germination, plant senescence and leaf abscission, stem elongation; plumular hook opening; leaf and cotyledon expansion, circadian clock, enzyme activation, gene activation/repression; transmembrane potential and anthocyanin synthesis.

Third light influences absorption of water and mineral nutrition by increasing in transpiration, respiration and photoassimilate translocation, contents of some plant hormones for instance IAA. If light intensity is too high, all above will be inhibited and senescence will be initiated. Superfluous light makes plant grow worse even die.

Fourth light often influence temperature and humidity both of which affect plant growth and development in great degree.

7. Analyze the reasons why field crop losses its green color in the field. (15 marks)

Plant factors and environmental factors cause field crop lose its green color in the field. For plant factors maturation and senescence are common. Most of plants appear yellow, orange or red upon maturation. Old leaf often loses green color when it naturally senesces. Main environmental factors causing loss of green color in field plants are mineral nutrition deficiency, which often can be found in old leaves for N, P, K, Mg, Zn deficiency, and young leaf for Ca, S, Fe and other microelements because those are constructers of plant body, regulators of life activity and/or homeostasis; Water deficiency and anaerobic conditions result in loss of green color of leaf because of biomembrane and organelle damage, metabolic and plant hormone disorder, mechanical injury in morphology, anatomy, toxification and energy deficiency or starvation. High or low temperature often causes change in state of lipid and protein denuturation, metabolic disorder, biomacromolecule degradation, toxification and starvation. Salty injury results in physiological drought, single salt toxicity and metabolic damage. Those factors all decrease in chlorophyll synthesis and aggravate chlorophyll degradation.

Air pollution, radiation injury, toxification of heavy metals even mineral elements and pest injury cause also chlorophyll degradation and plant senescence, which make field crops lose green color in leaves.

浙江大学2008–2009学年春夏学期

《植物生理学及实验》课程期末考试试卷(A答案)

开课学院：生命科学学院，考试形式：闭卷，允许带答题用笔入场考试时间：2009年6月22日10:30-12:30, 所需时间：120分钟

考生姓名：学号：专业：

题序得分评卷人

一二三四1 四2 四3 四4 四5 四6(7）总分一、 Choice (Select the best one of the following four answers, total 10 marks, one mark for each)

1. Plant tissue will 2 when it is put into a hypertonic solution.

(1) take up water (2) loss water (3) get water equilibrium (4) occur all above

2. The ascent of xylem sap is explained by combining 3 force of water when transpiration is strong.

(1) transpiration and root pressure (2) root pressure and cohensive (3) transpiration and cohensive (4) root pressure and tensive 3. Plant appears stun, less branches and tillerings. Leaves look yellow, especially for older leaf, and roots show thinner and longer. The symptoms are caused by 3 deficiency. (1) P (2) K (3)N (4) Mg

4. In the following salt groups, 4 belong to physiologically alkaline salt.

（1）NH4Cl、K2SO4 and (NH4)2SO4 （2）NH4Cl、K2SO4 and NH4HCO3

（3）NH4Cl、K2SO4 and NH4NO3 （4） KNO3、Ca NO3 and

CaHPO4

5. The enzyme for CO2 fixation in bundle sheath cell of C4 plant is

1 .

（1） PEPase （2） PGADH （3） Ru5P kinase （4） RuBPCase 6. Increase in CO2 concentration will 1 in light

compensation point.

(1) decrease (2) increase (3) be equal (4) all happen 7. The respiratory electron transport occurs in 2 . (1) Cytosol (2) thylakoid membrane

(3) mitochondrial matrix (4) mitochondrial cristae

8. The leaf photosynthetic rate will 1 if fruits or ears are removed from plant.

(1) be inhibited (2) be enhanced (3) be not changed (4) all happen

9. GA can promote the seed germination because it induces 2 .

(1) uptake of water (2) synthesis of amylase (3) stem elongation (4) imbibition

10. Microtubules are consist of 1 .

(1) tubolins (2) actins (3) microfilaments (4) intermediate filaments

二、Cloze (Fill the blank with suitable word(s) or phase(s), total 16 marks,

1 mark for each)

1. Plant metabolism is high and the growth rate is high , but its resistance is weak if the ratio of free water to bound water in plant is high.

2. The organs stem apical meristem response to vernalization

while the leaf response to photoperiodism.

3. Root/shoot ratio is influenced by nutrition , water , and light conditions.

4. Four-whorl model of flower development, sepal, petal, stamen and

carpel shows that gene type B controls petal , stamen and gene type C controls stamen , carpel . 5. Nitrate reductase catalyzes nitrate to form nitrite . 6. Seed dormancy is usually caused by seed coat limitation, and immatured embryo , or inhibitor .

三．Definitions (Choose 8 of 10 followings, total 24 marks, 3marks for each)

1. Soil available water:Soil available water (土壤有效水）is referred as the water

can directly be taken up and utilized by plants, whose water content is higher than wilting coefficient in the soil.

2. Essential elements:The elements, in brief, is necessary for plants to grow and

develop, including macroelements (C, H, O, N, P, K, Ca, Mg, S), and microelements (Fe、Mn、B、Zn、Cu、Mo、Cl、Ni)

3. Light harvesting pigments: Light-harvesting pigment(集光色素）或antenna

pigment（天线色素)——only play roles in light absorption and transfer but does not

undertake photochemical reaction, which are all Chlb and carotenoids, most of Chla.

4. Respiratory climacteric: In some species, fruit respirations begin to decline

with maturation of the fruits, but abruptly increase to a peak in the post ripening stage and decrease again. Such as apple, peach, pear, banana, strawberry etc.

5. Quantum efficiency: The plant assimilates number of CO2 by absorption of 1

molecule of quantum. It is 1/8 ~ 1/10 for C3 plants.

6. Oxidative phosphorylation:A process in which ATP is synthesized with ADP

and Pi, while the respiratory electron is transferred along respiratory chain to O2.

7.Partition:Distribution of photoassimilate in to different organs of plant is called

partiting

8. Polar transport: IAA is only one plant hormone transported unidirectionally

from apical end to basal end.

9. Development: the sum of all of the changes that an organism goes through in its

life cycle, including growth and differentiation. Ultimately, development is an expression of the genetic program that directs the activities and interactions of individual cells.

10. Tolerance:a resistant reaction to reduce or repair injury with morphology ,

structure, physiology, biochemistry or molecular biology, when plant counters with stresses.

四、Questions（Total 50 marks. 1-5 are necessary to answer, Choose one between 6 and 7）

1. Why do we often see that some plants wilt at noon but recover to normal at night in the sunny summer day? And what should you do to avoid this wilting? (5 marks)

It is temporary wilting caused by loss of equilibrium between water absorption and evaporation (main transpiration). At noon transpiration is larger than absorption and plant wilts. At night transpiration is equal to absorption, the wilt removes.

Normal status of leaf can be recovered by shading, or in the evening upon decreasing in transpiration.

2. Why is Rubisco considered as a key enzyme in the photosynthetic carbon cycle? ( 5 marks)

3. What is difference between growth inhibitors and growth retardants？(8 marks)

The main difference between growth inhibitors and growth retardants is their difference in the functioned parts and inhibition and recovering behaves. Growth inhibitors, such as TIBA and HM block apical meristem growth and the inhibition can be removed by IAA (IAA recovering).Growth redardants such as CCC, PP330 and PIX inhibit the subapical meristem and this inhibits can be removed by GA (called GA recovering).

4. How to improve resistance of plant to drought? (8 marks)

Resistance of plant to drought is the ability adaptive or tolerant to water

deficiency. Drought resistance depends on the plant types. Xerophilous plants have much higher resistant ability to drought stress than land plants. Even in land plants vary in species, varieties or cultivars. Therefore, (1)the best way is to select cultivars with high resistance to drought，high yield and quality. (2)The drought hardening, such as “seedling drought”, “seedling starvation” and “double sprout” is available to improve the ability. Seed priming, a special technology to control seed water absorption and re-drying slowly is also used in modern production to improve the resistance to drought stress. （3）Suitable fertilizer such as K and P etc application in can also improve resistance of plant to drought. （4）Chemical regents，such as soaking seeds in 0.25% CaCl2 or 0.05%ZnSO4 solution can be applied upon low available water in the soil. Application of plant substance ABA, CCC etc is

recommend for avoiding air drought. (5) Drought resistant genes, for instance, DRE and relevant synthases of proline, glycinebetaine Lea protein, dehydrin, osmotin can be transferred into the potential plants.

5. What is the law of assimilate distribution? How to use the principle in production? (9 marks)

The law of assimilate distribution is “Source to sink, provide prior to growth center”, “Ipsi-lateral transport, near supplication prior to the sink next to source”. Here leaf is source and fruit or ear is sink.

Therefore we should maintaining the function of flag leaf and fruit leaf, and protect them from damage of abiotic or biotic stresses and delay them senescence because they are most strong and near source. When it is limited, the photoassimilate first provide the growth center, which is a part growing fast and getting assimilate easily at the special time.

We often remove overgrowing buds and apical buds for more fruit setting and sometimes thin the flowers and fruits if plants have not enough source leaf.

6. Describe physiological and biochemical changes during leaf senescence and how to delay leaf senescence (15 marks).

During leaf senescence happen lots of physiological and biochemical changes. (1) Photosynthesis declines with slower phase and faster phase because of decrease in activity and content of photosynthetic key enzyme (Rubisco) and in activity of photoelectron transport and photophosphorylation. Chlorophyll content and stomatal conductance decrease in yellow leaf. (2) Membrane and organelle senescence appear and hydrolase activities rise, resulting membrane leakage and metabolism disorder, biomolecules degradation.

(3) Organelle degradation can be seen in order from thylakoid to ER, to Ribosome, to mitochondrion, to vacuole degradation and form plastoglobulus.

Therefore, we should do several aspects for delaying leaf senescence.

First, we should use germplasms resistant to senescence by selection of varieties and cultivars resist to senescence because most plants have their resistant variety or cultivar we can use.

Third, Application of plant substances for resistance to senescence is also available such as utilization of CTKs，BRs，polyamines，IAAs for different plants.

7. Describe the roles of vernalization and photoperiodism on the plant development in theory and production? (15 marks)?

Vernalization refers low-temperature promotion of flowering in the past, but it includes low temperature promotion of any developmental events now. Photoperiodism refers the response of plant flower (development) to photoperiod (day length of 24 h cycle).Both plays very important role on plant development in theory and production.

Not only is it found for flowering of some of plants including winter annuals,biennials and perennials but also scientists have uncovered the characteristics of vernalization, such as the

relationship between temperature and time during the vernalization, the parts and ages sensitive to low temperature and possible mechanisms and some genes for vernalization in theory. Farmers can used vernalization and devernalization to control plant growth and developments, such as to sow winter wheat in spring after germinating seeds treated with low temperature and harvest

larger angleca or onion with high temperature in winter. It is used to select sowing time according to different types and characters of plants and to induce crop from one place to others.

For photoperiodism 3 basal types (SDP、LDP and DNP) and other types have been known in base on the requirement of day length and night length for plant flowering.Critical night length is determiner for plant flowering and phytochrome, a complex of chromophore and protein, participates this reaction. special genes have been cloned and stimulus of floral---Florigen or inhibitors of floral are hypothesized. The principles are also applied in production to (1)

Introducing crops. If you want to harvest seed of plant, you must obey the law of the inducing

crops in the Northern Hemisphere. It is that SDP induced from south to north, growth stage longer, early matured cultivar can be done. On contrary, from north to south, growth stage shorter, lately matured cultivar can be done. LDP induced from south to north, growth stage shorter, lately matured cultivar can be done. On contrary, from north to south, growth stage longer, early

matured cultivar can be done. However, you often induce crop belonging SDP from south to north to harvest larger vegetative body such as sugarcane. (2) Selecting suitable sowing stage and controlling flower time.SDP or LDP or Genetic male sterility induced by day length need to sow different seasons. (3)Regulation of flower time for hybrids seed production , flash flower production by SD or LD treatments.

浙江大学2009–2010学年春夏学期

《植物生理学及实验》课程期末考试试卷(Ａ)

开课学院：生命科学学院，考试形式：闭卷，允许带答题用笔入场考试时间：2010年７月6日10:30-12:30, 所需时间：120分钟

考生姓名：学号：专业：

题序得分评卷人

一二三四1 四2 四3 四4 四5 四6(7）总分一、 Choice (Select the best one of the following four answers, total 10 marks, one mark for each)

1. When plant faces to water deficiency，stomatal conductance often 2 .

（1）increases （2）decreases （3）little changes （4）opens 2. When the ratio of free water to bound water keeps lower, the plant usually shows 2 .

(1)high metabolism and low resistance (2)low metabolism and high resistance

(3)high both metabolism and resistance (4)low both metabolism and resistance

3. In those elements below， 4 belong to macroelements. （1）B, N and Mg （2）Fe, Ca and N （3）Fe, N and S （4）C, H and O

4. Oxygen evolution take place in 4 。（1）chloroplast envelope （2）chloroplast stroma （3）mitochondrion matrix （4）thylakoid lumen

5. At night CAM plant accumulates lot of 3 in vacuole. （1）amino acid （2）citrate （3）malate （4）CO2

6. In the below light range 3 shows lowest influence on plant growth and development.

（1）Far red light （2）red light （3）green light （4）blue light

7. In anaerobic condition, normal respiratory rate drops and substrate degradation rate 2 .

（1）decreases （2）rises （3）does not changes （4）both (1) and (2)

8. During filling stage in germanous，the growth center is 3 。（1）flag leaf （2）stem （3）grain （4）root 9. CTK is mainly synthesized in 4 .

（1）stem apices （2）leaf （3）fruit （4）root tip

10. In the following methods 1 can break legume hard seed dormancy.

（1）scarification, hot water or H2O2 treatment （2）scarification, stratification or H2O2 treatment （3）stratification or GA treatment

（4）drying under strong sun light or GA treatment

二、Cloze (Fill the blank with suitable word(s) or phase(s), total 16 marks, 1 mark for each)

1. The plants are not easily injured by low temperature if higher contents of unsaturated fatty acid in the membrane lipids.

2. In practice short day plant induction from south to north, we should select early ripening cultivars, while we should do late cultivars from north to south.

3. Plant organ correlations often show shoot and root , main stem and

branch and vegetative and productive organs .

4. ABA can inhibits synthesis of α-amylase (enzyme)，as an antagonism to plant hormone GA .

5. In aerobic condition oxidative phosphorylation from NADH to Cytaa3

produces P/O is 3 . 6. In comparison with C3 plants，C4 plants appear higher light saturation point， lower CO2 compensation point and lower photorespiration rate.

7. In guard cell CO2 rising , K+ decreasing , water content decreasing or ABA increasing all make stomata closure.

三．Definitions (Choose 8 of 10 followings, total 24 marks, 3 marks for each)

1. Bound water: It tightly binds to components of cell and can not move freely in plant. 2. Aquaporins: Aquaporins in all living cell are a serious proteins which located in plasmatic membrane or tonoplast, and play an important role in water transmembrane transport because they have less resistance to water and speed up water transport across the membrane.

3. Foliar nutrition: Foliar nutrition is a method in which the fertilizer is applied to plant shoot, usually to leaves, in agricultural production.

4. Reaction center pigments: They can absorb light energy (or accept the energy transferred from the antenna pigment) and then convert that into electric energy. They are a few of chlorophyll a.

5. CO2 compensation point: As CO2 decreases, photosynthetic rate decreases. CO2 concentration at which fixation of CO2 by photosynthesis is equal to release of CO2 by respiration, or net photosynthetic rate reaches zero is called CO2 compensation point.

6. RQ (respiratory quotient): or Respiratory coefficient is referred as the ratio of moles (or volumes) of released CO2 to absorbed O2 by plant tissue at the same time.

7. Triple response: A typical reaction of plant to ethylene represents inhibition and swelling of hypocotyl, inhibition of elongation, and exaggeration of the curvature (leaf epinasty). 8. Optimum temperature for growth: it is the temperature at which plant grows fastest but not strongest.

9. Critical night length: it referred as the night length of 24h cycle, the shortest length for inducing SDP flowering and the longest length for inducing LDP flowering.

10. Stress: Stress in biology is any change in environmental conditions that might reduce or adversely change a plant’s growth or development.

四、Questions（Total 50 marks. 1-5 are necessary to answer, Choose one between 6 and 7）

1. What will appear in plants upon N-over or -deficient（5 marks）? N-over results in plant overgrowth with deep green color and soft in leaf and infected

easily by plant diseases and damaged by insects. Plants appear lower setting rate or lower

fruit setting and delay ripening.

N-deficiency makes plant growth stun with yellow leaves, old leaf die easily and root and branch develop poorly.

2. Which phases may aerobic respiration in plants be divided into and which part is each phase located in（5 marks）?

There are several phases: EMP in cytosol, citrate cycle in matrix of mitochondrion, respiratory electric transport and oxidative phosphorylation in cristae of mitochondrion.

3. How do IAA polar transport and WUS expression control apical differentiation（6 marks）?

Stem apical differentiation are controlled by IAA polar transport. Leaf differentiation needs

IAA polar transport from center cone to outsides which leaf primordium differentiates and develops. A suitable concentration of IAA in the center cone regulates WUS expression which increases in number of stem cells. The stem apical grows. In the stem cell CLV3, a small peptide combining with CLV1,another small peptide inhibits WUS expression and decrease in number of stem cell. Leaf primordium differentiates and develops again. A new cycle begins.

4. Give two examples for promotion of shoot-root ratio and explain why they can do it in physiology（8 marks）.

(1) Select two of in water or nitrogen or in decrease PK application and explain them.

Such as (1) the increase in water supplying can enhance the shoot-root ratio. It promotes shoot growth due to enough water and inhibits photoassimilate transport into root. Under less water conditions root can easily get water from the soil in which root system anchor. Lower water content in the soil results in increase in soil oxygen which induces increase in aerobic respiration of root. These enhance root develop better than water sufficiency. (2) Decrease in K application can enhance the shoot-root ratio, too. K application promotes photosynthesis of leaves and photoassimilate can be easily transported out of leaf (shoot) to root because K can promote sugar into SE/CC in phloem as a counter ion.

(Other reasonable answers are available, too.)

5．Explain following picture according to law of photoassimilate

distribution, and how to confirm your hypothesis with an experiment (10 marks) ?

1, 2 are two fruits in flowering in the same day, but grew significantly different in size after 10d fertilization.

The law of photoassimilate distribution source to sink prior to growth center. The growth center is a part fast growing and getting assimilate easily at the special time. The picture showed two fruits 1 and 2 growing in same vine. The two fruits are two sinks. Fruit 2 is large sink becoming growth center, easily gets photoassimilate from leaf (source) and growth fast. Fruit 1 only get a little photoassimilate from leaf and grows slowly.

Confirm your hypothesis with an experiment: Feeding 14CO2 to source leaf and determine 14C-photoassimilate distribution. We can find most of 14C accumulate in fruit 2 and small of them accumulate in fruit 1.

Second, removing the fruit 2 and fruit 1 will grows fast.

6. How do you increase physiologically in photosynthetic productivity

(16marks)?

Photosynthetic productivity is total biomass produced by photosynthesis. Therefore increase in photosynthetic productivity is mainly contributed to increase in photosynthesis. Photosynthesis is influenced by inner factors and environmental factors.

Photosynthetic productivity is not high enough because of those reasons: (1) Lower net photosynthetic rate (Pn) of single leaf.

(2)Lower Pn of plant canopy (populations), resulting in much leakage of sunlight,

higher transmittance or/and reflectance of light by leaf, and light-saturation for carbon fixation.

(3) No enough accumulation of assimilate in products.

Therefore, increase in photosynthetic productivity in physiology and production can

be considered as followings:

(1) Increase in Pn of leaf includes higher ability of light absorption, transfer under lower light condition, such as higher photo-electron transport and photophosphorylation, less photoinhibition under higher light condition, and higher activity of enzymes for carbon fixation (especial Rubisco and its activase) etc by selection of higher Pn varieties and some transgenic plants. Transgenic plants may be

used for increase in PEPCase in C3 plants in future. Improving Rubisco may be used for decreasing oxygenase activity and increasing carboxylase activity so as to decrease in photorespiration.

(2)Increase in Pn of plant canopy includes increase in leaf area by a suitable planting density, and good application of fertilizer and utilization of erect plant type, extending of photosynthetic time by enhancing planting system, such as increase in multiple crop index, intercroping and using variety with longer growth period, and decrease in photorespiration and respiration by selection of higher Pn varieties and some transgene plants.

(3) Increase in accumulation of assimilate in productive organ includes promotion of harvest index by using better variety, good conditions for setting, such as application of mineral nutrition, light, CO2, water and temperature etc.

7. Describe physiological and biochemical events during senescence（16 marks）.