8 Photosynthesis - Browser Expressaer2.sbc.edu.hk/~bio/F.4/Practice Book A…  · Web view · 2006-12-19It is because green plants on the earth carry out photosynthesis which takes

8 Photosynthesis Class Practice8.1 How do green plants feed?

8.2 The requirements for photosynthesis1. (a) carbon dioxide

(b) water(c) solar energy/sunlight(d) carbohydrates/glucose(e) Oxygen

2. (f) mesophyll3. (g) stomata

8.3 Investigations to study the requirement for photosynthesisA. Multiple Choice Questions

1. D2. C

B. Structured Questions1. (a) 1 4 3 2

(b) to soften the leafto extract chlorophyll/decolourise the leaf

2. (a) to destarch the plant(b) (i) to show that carbon dioxide is necessary for photosynthesis

(ii) to absorb carbon dioxide(c) (i) to show that light is necessary for photosynthesis

(ii) to exclude light / make sure the plant cannot absorb light(d) Leaf A - blue black, leaves B and C - brown

8.4 The photosynthetic process1. F

2. T3. F4. F

1. The chlorophyll mainly absorbs red and blue light of the spectrum for photosynthesis. Most of the green light is reflected.

3. During the light reactions, water is split into hydrogen and oxygen. Oxygen is released immediately and hydrogen combines with carbon dioxide to form carbohydrate in the dark reactions.

4. Dark reactions immediately occur after the light reactions. They both take place in the daytime.

8.5 The effects of environmental factors on the rate of photosynthesis(a) When the distance between the beaker and the table lamp increases, the

light intensity decreases. Therefore, the rate of photosynthesis decreases with the increase in distance.

(b) This solution provides carbon dioxide.(c) A large beaker can hold a greater volume of dilute sodium

hydrogencarbonate solution. This provides more carbon dioxide and absorbs more heat energy released by the table lamp.

(d) Crops grow faster in a greenhouse because it is warmer inside. The carbon dioxide concentration can also be increased in a greenhouse to increase the photosynthetic rate of the crops.

8.6 The products of photosynthesisA. 1. A

2. AB. 1. F

2. T3. F4. F5. T6. T

1. Some of the oxygen produced during photosynthesis is used for respiration. The rest of it diffuses out into the atmosphere.

3. Sucrose can be carried to actively growing regions where it is changed to glucose.4. Plants make use of glucose to make many organic substances in

addition to starch and sucrose.

8.7 Leaves-organs of photosynthesis

A. 1. B2. A

B. (a) i. veinsii. cuticleiii. epidermisiv. palisade mesophyllv. spongy mesophyllvi. xylemvii. phloemviii. stoma

(b) 1. Gases can diffuse into and out of the leaf easily.2. Diffusion is faster and more sunlight can be absorbed.3. to carry water and minerals from the soil to the leaf4. to carry the product of photosynthesis away from leaf

5. for gaseous exchange, to allow carbon dioxide in the atmosphere to diffuse into the leaf

6. to prevent excess water loss7. for diffusion of gases

Exam PracticeA. Multiple Choice Questions

1. B2. D3. A4. B5. B6. C7. D8. D9. D10. B

B. Structured Questions1. (a) Structure X is chloroplast.

(b) A water

B oxygenC carbon dioxideD glucose/carbohydratesM hydrogen

(c) stoma

(d) for respiration to release energyto form chlorophyll with magnesiumto form amino acids with nitrates

(e) Stage I - light reactions Stage II - dark reactions2. (a) (i) variegated leaf

(ii) to remove the chlorophyll and make the results more obvious(iii) heat the leaf in alcohol(iv)

(b) (i)

(ii) (1) chlorophyll(2) carbon dioxide

(3) light

C. STS Connections

blue black brown/yellow

blue black

brown/yellow

1. No. It is because green plants on the earth carry out photosynthesis which takes up carbon dioxide and releases oxygen. Therefore, the amount of oxygen is balanced by photosynthesis and oxygen would not be depleted.

2. (a) Glucose/carbohydrates(b) Yes. Green plants turn solar energy to chemical energy which further

transfers to other organisms. Moreover, green plants balance the amount of oxygen and carbon dioxide in the atmosphere to ensure sufficient oxygen for the occurrence of respiration.

Class and Exam Practice 2 9 Respiration Class Practice9.1 What is respiration?

1. F2. T3. T

4. F5. F

6. T7. F8. T

1. All living cells require energy.4. The process of burning is different from that of respiration.5. Burning cannot occur inside a cell even if a sufficient amount of oxygen is

present.7. The reactions of respiration are controlled by enzymes while burning does

not involve enzymes.

9.2 The use of energy released from food

9.3 The chemistry of respiration1. F

2. T3. T4. F5. T6. F7. T

8. F9. T

1. Respiration in plants occurs all the time.4. ATP stores energy for a short period only.6. ATP is made inside the mitochondria.8. ATP cannot be transported from cell to cell. It has to be used inside the cell

in which it is made.

9.4 Aerobic and anaerobic respirationA. 1. (a) glucose

(b) carbon dioxide(c) aerobic

2. (d) glucose(e) ethanol(f) alcoholic fermentation

3. (g) lactic acid(h) lactic acid fermentation

B. 1. T2. F3. F4. F5. T

2. Mitochondria are involved in aerobic respiration only.3. Skeletal muscles carry out aerobic respiration if sufficient oxygen is available.4. Mitochondria are present in muscle cells.

Exam PracticeA. Multiple Choice Questions

1. C2. B3. D4. C5. D6. B7. A8. D

9. B10. C

B. Structured Question1. (a) food + oxygen carbon dioxide + water + energy

(b) oxygen(c) The oil drop would move towards the boiling tube. The small insect

takes up oxygen during respiration and gives out carbon dioxide which is then absorbed by the soda lime. As a result, the air pressure inside the boiling tube becomes lower than the atmospheric pressure and the oil drop moves towards the boiling tube.

(d) To eliminate the error caused by environmental factors such as temperature and pressure.

(e) The oil drop moves faster towards the boiling tube because the rate of respiration of the small insect is faster at higher temperatures.

(f) to prevent the small insect from touching the soda lime2. (a) The bulb of the thermometer should be immersed into the solution in

order to detect the temperature change of the yeast and glucose solution.The conical flask should be wrapped by cotton wool / the conical flask should be replaced by a thermos flask so as to prevent heat loss.

(b) (i) carbon dioxide(ii) Solution X is lime water. It turns milky.

OR Solution X is hydrogencarbonate indicator solution. It turns from red to yellow.(c) To prevent the solution from coming into contact with air.(d) Boiling the glucose solution drives off any dissolved oxygen.

3. (a) The germinating seeds took up oxygen during respiration and gave out carbon dioxide which was then absorbed by the sodium hydroxide solution. As a result, the air pressure inside flask A became lower than that of the atmosphere and the coloured water moved up the glass tube X.

(M – N) R(b) ————— cm3/h

2(c) Oxygen had been used up and only anaerobic respiration occurred.

The sodium hydroxide solution absorbed the carbon dioxide

produced.4. (a) The potassium hydroxide solution in flask A removes carbon dioxide

from the incoming air. The lime water in flask B is used to show that the incoming air is free of carbon dioxide.

(b) The bell jar should be covered with black paper or black cloth in order to exclude light. Otherwise, the potted plant will undergo photosynthesis and absorb carbon dioxide.

The pot should be covered with a polythene bag to prevent the soil micro-organisms from carrying out respiration and releasing carbon dioxide.

(c) The lime water in flask C turns milky.This shows that carbon dioxide has been produced by green plants in

the dark.

C. STS Connections(a) Aerobic exercises

(b) Glucose / carbohydrates(c) Glucose + oxygen carbon dioxide + water + energy (heat and ATP)

(d) Aerobic respiration is carried out and hence no lactic acid is accumulated.

10 Obtaining essentials for life in green plants

Class Practice

10.1 Nutrition1. T

2. F3. T4. F2. Green plants synthesise organic substances by using simple inorganic

substances from their surroundings. Energy is needed in this process.4. Animals, fungi and most bacteria are heterotrophs.

10.2 The importance of minerals for proper growth in green plants1. (a) active transport

2. (b) major elements(c) trace elements

3. (d) proteins(e) nitrates(f) small leaves

(g) weak stems4. (h) chlorophyll

(i) poor growth(j) yellowing of leaves

10.3 Fertilizers1. T

2. T3. F4. F5. T

3. The proportion of nitrogen, phosphorus and potassium in chemical fertilizers is not always the same.

4. Natural fertilizers have to undergo decay and release mineral salts slowly. They cannot be used immediately.

10.4 Gaseous exchange in plants

A. 1. (a) stomata(b) diffusion

2. (c) spongy(d) air space

3. (e) cork cells(f) lenticels

B. 1. F2. T3. F4. F

1. Green plants carry out respiration all the time.3. The rate of respiration in plant cells is more or less constant throughout the day.4. At compensation point, the rates of photosynthesis and respiration are equal.

10.5 TranspirationA. 1. D

2. D3. A4. C

B. 1. F2. T

3. T4. F5. T

1. During transpiration, transpiration stream carries water and dissolved mineral salts from the roots to the leaves.

4. The higher the temperature, the greater is the rate of transpiration because water evaporates faster.

10.6 Absorption of water and mineral salts by the root1. C2. F3. E4. G5. H6. D7. A8. B

10.7 Transport in flowering plants1. F

2. F3. T4. T5. F

1. Xylem is made of vessels and each vessel is made up of many dead cells which are joined end to end.

2. Xylem vessels run from roots, up through the stem, and finally branch out into every leaf.

5. Sieve tubes are living cells with cytoplasm.

10.8 Support in plants(a) turgidity — A and D

rigidity — B and C(b) Most of the cells become flaccid because the rate of transpiration is faster

than that of water absorption. The plant will wilt.

Exam PracticeA. Multiple Choice Questions

1. C2. A3. C4. D5. B6. B7. A8. C9. B10. B

B. Structured Questions1. (a) (i) Set-up C

(ii) Set-up B(iii) Set-up A

(b) Set-up A: The leafy shoot should be cut under water to ensure the xylem is not blocked by air. The oil must be poured onto

the water after the plant has been put into the measuring cylinder.

Set-up B: The leaf must be fixed so it cannot slide on the needle.Set-up C: The shoot must be cut and fitted under water to prevent

bubbles from entering the xylem of the shoot.(c) (i) to balance the weight of the leaf

(ii) to prevent evaporation of water in the measuring cylinder(d) No, it is not necessary because the water in the reservoir will not be

measured.2. (a) A is root hair.

It increases the surface area for absorption of water and mineral salts.(b) The water potential of the soil water is higher than that of the

cytoplasm and the cell sap of the root hairs. Water enters the root hairs and epidermal cells by osmosis.

(c) Soil air supplies oxygen for the cells in the root to carry out respiration.

(d) Y is xylem vessels.They carry water and mineral salts from roots to the leaves. They provide

mechanical support to the plant.3. (a) in the daytime, warm and moving air

100(b) —— = 25 mm/minute

4

(c) The rate of the movement of the air bubble will be much slower. It is because the relative humidity inside the plastic bag is high / the air inside is saturated with water vapour. Water vapour from the air space will not diffuse out easily.

(d) The transpiration stream carries dissolved mineral salts from the roots to the leaves. Transpiration helps the absorption of water and minerals from the soil. It also produces a cooling effect.

4. (a) Air should be pumped into the solution / aeration. This ensures that the roots get enough oxygen for respiration.

The conical flask should be wrapped with aluminium foil. This prevents algae from growing in the flask.

(b) poor growth and yellowing of leaves

B. STS Connections

(a) (i) (ii)

(b) The thin film of moisture around mesophyll cells evaporates into the intercellular spaces and diffuses out of the stomata into the atmosphere.

(c) Light intensity. The higher (lower) the light intensity, the larger (smaller) are the guard cells and the wider (smaller) the stomata. More water vapour can diffuse out. Transpiration rate increases.

11 Food requirements in humans

Class Practice

11.1 Heterotrophic nutrition

11.2 Food and food substances1. F2. T3. F4. T5. F

1. Most heterotrophs are animals. (Some saprophytic fungi are also heterotrophs.)3. The food we eat every day make up our diet.5. As vitamins, minerals and dietary fibres are necessary for keeping us

healthy, they are called protective food substances.

11.3 CarbohydratesA. 1. T

2. T3. F4. F5. T6. F7. T

3. In disaccharides only sucrose is non-reducing sugar.4. Both hydrolysis and condensation require the presence of suitable enzymes.6. Polysaccharides do not give a sweet taste.

B. 1. F2. C3. D4. E5. B6. A

11.4 Fats

11.5 Proteins1. T

2. F3. T4. F5. T6. F

2. A molecule of fat is made up of three molecules of fatty acid combined with one molecule of glycerol.

4. Essential amino acids cannot be made in human body.6. The excess amino acids are broken down in the liver by deamination.

11.6 Vitamins1. T

2. F3. F4. T5. F6. T7. F

2. Plants can make their own vitamins from simple substances.3. Fat-soluble vitamins are more heat resistant than water-soluble vitamins.5. Lack of vitamin A causes night blindness.7. Vitamin D helps the absorption of calcium and phosphorus in the small

intestine.

11.7 Mineral salts

11.8 Dietary fibres

11.9 Water1. C

2. A3. C4. B5. D

11.10 Food tests(a) Clinistix paper(b) colour changes from pink to blue(c) Benedict's test(d) formation of brick-red ppt.(e) iodine test(f) colour changes from brown to blue black(g) Albustix paper(h) colour changes from yellow to green(i) spot test(j) formation of permanent translucent spot(k) DCPIP test(l) The blue DCPIP is decolourised

11.11 The need for a balanced diet

11.12 Food and energyA. QSRPB. 1. P

2. QC. 1. F

2. F3. F4. T5. T

1. A balanced diet contains the right amount of all the food substances.2. A pregnant woman needs extra food because she needs more energy for

the growth of the foetus.3. Energy for living comes from carbohydrates, fats and proteins.

11.13 The health problems resulting from an improper diet1. C

2. D3. B

4. A

Exam PracticeA. Multiple Choice Questions

1. D2. C3. C4. B5. A6. B7. B8. D

B. Structured Questions1. (a) 430

370320278252230430370320278215182

(b)

(c) 3 years of age.Children need to maintain a higher metabolic rate in order to support their period of greatest growth / compensate for the higher rate of heat loss.

(d) After the age of 14, boys are more active than girls. Girls have thicker subcutaneous fat so that the rate of heat loss is lower than that of boys. Girls require less energy than boys.

2. (a) The calcium requirements of group II is greater than that of group III, because group II requires more calcium for the development of bones.

15(b) (i) Group I: —— = 2

7.5

20Group II: —— = 1

20

50Group III: —— = 0.83

60

45Group IV: —— = 0.9

50Therefore, group I requires the greatest amount of protein per unit weight.

(ii) Group I grows faster than other groups. Protein is important for growth.

(c) People in group III are more active and they have thinner subcutaneous fat.(d) Girls lose blood every month / during menstruation. Iron is important

for the formation of red blood cells / haemoglobin.3. (a) B contains reducing sugar and vitamin C.

C contains protein and fat.(b) butterfruit / orange / kiwipork / beef / fish(c) food sample D(d) The blue DCPIP becomes colourless.(e) In cold areas, people lose heat at a faster rate. Food sample A contains

fat which can release much more energy to compensate for the heat loss.

4. (a) W — fats, X — carbohydrates, Y — water, Z — proteins(b) Beans also contain mineral salts and vitamins which are not shown in

the table.(c) (i) butter

(ii) cabbage(d) Beans. Beans contain the highest percentage of carbohydrates which

can supply energy. Beans also have a relatively high percentage of proteins for growth.

5. (a) too much carbohydratestoo much fatabsence of dietary fibresabsence of vitamin C

(b) Eat less french fries.Use less sugar for coffee.Eat fresh fruits or vegetables.

any three}

(c) Constipation — absence of dietary fibresScurvy — absence of vitamin C

C. STS Connections(a) D

BC

(b) No, it is not a balanced diet. It does not contain any cereals or grains which should be in the greatest amount in a balanced diet. It has too little fruits and vegetables, and too much meat.

(c) It supplies inadequate energy for metabolism and daily activities. It contains too little cellulose and hence would result in constipation.