Class: Name: Date: 9 Nutrition and gas exchange in plantsbio662.dyndns.info/DSE/WS/ws_ch09_e.pdf · 26 guard cells 27 stomata 28 lenticels 29 cuticle 30 oxygen 31 carbon dioxide 32

Class: Name: ( ) Date:

New Senior Secondary Mastering Biology Oxford University Press 2014 (Second Edition)

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9 Nutrition and gas exchange in plants

9.1 Nutrition in plants (Book 1B, p. 9-3)

A Plants as autotrophs (Book 1B, p. 9-3)

� Plants can make their own food (in the form of (1) _______________) from

(2) _______________ _______________ and water using light energy through the process of

(3) _______________.

carbon dioxide + water carbohydrates + oxygen

light energy

chlorophyll

� The light energy is trapped by the (4) _______________ in plants. (5) _______________ is

released as a by-product (副產物).

� Plants absorb (6) _______________ (礦物質) from the soil. They are vital for the synthesis of

other materials needed by the plants.

oxygen

(into the air)

light

chlorophyll

photosynthesis

carbon dioxide (from air)

minerals (from soil)

water (from soil)

inte

rmed

iate

s

carbohydrates

lipids

proteins

plant materials,

e.g. enzymes,

chlorophyll,

cell membrane and cell wall

▲ Plants make their own food by photosynthesis


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� Since plants are able to use simple inorganic substances to make the (7) _______________

substances (e.g. carbohydrates) they need, they are known as (8) _______________ (自養生物).

Their mode of nutrition is called (9) _______________ _______________ (自養營養).

� Plants are (10) _______________ (生產者). They serve as the basic food source for other

organisms.

B Mineral requirements of plants (Book 1B, p. 9-4)

� For healthy growth, plants need to absorb a variety of (11) _______________ in the form of

(12) _______________ (離子) from the soil.

� The elements that form these mineral ions can be divided into two types:

(13) _______________ elements (大量元素) and (14) _______________ elements (微量元素).

� Examples of major elements and their importance on plant growth:

Element Main function Deficiency symptom

Nitrogen

(N)

� For the synthesis of

(15) _______________

� Poor growth

� (16) _______________

leaves

Phosphorus

(P)


(17) ______________ _____________

� Required in some enzymatic reactions

� Poor growth, particularly

of (18) _______________

� (19) _______________

patches on leaves

Potassium

(K)

� Promotes photosynthesis and the

transport in plants

� Required in some enzymatic reactions

� Poor growth

� Curled-up leaves with

dark-coloured edges

Magnesium

(Mg)


(20) _______________

� Poor growth

� Yellow leaves

� Go to

Practical 9.1 Design an investigation of the effects of different minerals on plant growth

(Book 1B, p. 9-6; Practical Workbook for SBA 1B, p. 9-1)


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9.2 Gas exchange in plants (Book 1B, p. 9-8)

� Plants exchange gases with the surrounding air by (1) _______________.

� In terrestrial plants, (2) _______________ are the main sites of gas exchange. Gas exchange

also takes place through (3) _______________ and (4) _______________.

1 Gas exchange in leaves

� Structure of a dicotyledonous leaf:

midrib (中脈)

network of veins

leaf blade

air space

cuticle

(8) _______________

(角質層)

vascular

bundle (維管束)

upper epidermis

(上表皮)

(5) _______________

_______________

(柵狀葉肉)

(6) _______________

_______________

(海綿葉肉)

lower epidermis

(下表皮)

(7) _______________

(氣孔)

xylem (木質部)

phloem

(韌皮部)

(9) _______________

_______________

(保衛細胞)

Structure Feature and function

Cuticle � A thin waxy layer covering the epidermis

� Reduces (10) _______________ loss from the leaf surface

Upper and

lower epidermis

� Protect the inner layers of cells

� No chloroplasts except the (11) _______________ _______________


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Palisade

mesophyll

� Made up of tightly-packed cylindrical cells that contain many

(12) _______________

Spongy

mesophyll

� Made up of irregularly-shaped cells that contain fewer chloroplasts

� Many (13) _______________ _______________ among the cells

Stoma

� Pore on the epidermis where (14) _______________ _______________

takes place

� Each surrounded by two (15) _______________ _______________

Guard cell � Contains chloroplasts

� Controls the opening and closing of the stoma

Vascular bundle � (16) _______________ transports water and minerals

� (17) _______________ transports food

� How gas exchange takes place in leaves:

Gases in

3

Gases out

2

1 iii

ii

i

Gases in Gases out

1 Gases from the environment diffuse into

the air space through the

(18) _______________.

2 Gases (19) _______________ in the moist

surface of the mesophyll cells and diffuse

directly into the cells.

3 Gases diffuse to the neighbouring cells.

i Gases produced by the cells diffuse to the

neighbouring cells.

ii Gases diffuse to the moist surface of the

mesophyll cells.

iii Gases diffuse into the

(20) _______________ _______________

and diffuse out.


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� Structural adaptation of leaves for gas exchange:

Feature Adaptation

Broad and flat leaves Provide a large (21) _______________

_______________ for gas exchange

Thin leaves Reduce the diffusion distance of gases

Many (22) _______________

_______________ among the spongy

mesophyll cells

Allow gases to diffuse freely

(23) _______________ surface of

the mesophyll cells

Allows gases to (24) _______________ in it and then

diffuse into the cells easily

Presence of (25) _______________

on the epidermis

Allow gases to pass into and out of the leaves freely

Presence of (26) _______________

_______________

Regulate the rate of gas exchange by controlling the

opening and closing of stomata

2 Gas exchange in stems and roots

� In herbaceous plants (草本植物), the stems also have (27) _______________ for gas exchange.

� In woody plants (木本植物), gas exchange also takes place through small broken parts in the

cork layer called (28) _______________ (皮孔) on the stem.

� Roots are not covered by (29) _______________. Gas exchange takes place all over their

surfaces.

3 What is the effect of light intensity on gas exchange in plants?

� Plants produce (30) _______________ and consume (31) _______________ ______________

during photosynthesis. They produce (32) _______________ _______________ and consume

(33) _______________ during respiration. The net uptake and release of gases by a plant

depend on which process occurs at a faster rate.

� (34) _______________ takes place all the time at a rather constant rate. However, the rate of

(35) _______________ is greatly affected by light intensity (光強度). Therefore, the net uptake

or release of gases by a plant would be affected by light intensity.


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At high light intensity

(e.g. in the daytime)

At low light intensity

(e.g. at night)

photosynthesis

CO2

O2

net exchange

of gas

net release of O2

net uptake of CO2

respiration

O2

CO2

photosynthesis

stops

net exchange

of gas

net uptake of O2

net release of CO2

respiration

O2 CO2

� The rate of photosynthesis is

(36) _______________ (higher / lower)

than that of respiration.

� As a result, there is a net

(37) _______________ (uptake / release)

of carbon dioxide and a net

(38) _______________ (uptake / release)

of oxygen.

� (39) _______________ stops and only

(40) _______________ occurs.

� As a result, there is a net

(41) _______________ (uptake / release)

of oxygen and a net

(42) _______________ (uptake / release)

of carbon dioxide.

� The relationship between light intensity and carbon dioxide exchange in a plant:

A B C D E

light intensity darkness

compensation point

net release of CO2

net uptake of CO2


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Description

A

CO2

O2

In the dark:

� Only (43) _______________ takes place

� The plant releases carbon dioxide and takes in oxygen

B

CO2

O2

Light intensity slowly increases as the morning comes:

� Photosynthesis takes place at an increasing rate, using up more and

more carbon dioxide

� Carbon dioxide released in respiration remains (44) ______________

� Net release of carbon dioxide and net uptake of oxygen decrease

C

At (45) _______________ _______________ (補償點):

� The rate of photosynthesis is (46) _______________ to the rate of

respiration

� No net exchange of gases

D

CO2

O2

Light intensity increases further:

� Photosynthesis occurs at a (47) _______________ rate than

respiration

� Net uptake of carbon dioxide and net release of oxygen

E CO2

O2

Light intensity increases even further:

� Net uptake of carbon dioxide does not increase

� Another factor (e.g. carbon dioxide concentration) limits the rate of

(48) _______________

� Go to

Practical 9.2 Examination of the structure of leaves


Practical 9.3 Investigation of the effect of light intensity on gas exchange in plants using

hydrogencarbonate indicator


Practical 9.4 Investigation of the effect of light intensity on gas exchange in plants using a

data logger



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Answers

Ch 9 Nutrition and gas exchange in plants

9.1 1 carbohydrates 2 carbon dioxide 3 photosynthesis 4 chlorophyll 5 Oxygen

6 minerals 7 organic 8 autotrophs 9 autotrophic nutrition

10 producers 11 minerals 12 ions 13 major 14 trace

15 proteins 16 Yellow 17 nucleic acids 18 roots 19 Purple

20 chlorophyll

9.2 1 diffusion 2 leaves 3 stems 4 roots 5 palisade mesophyll

6 spongy mesophyll 7 stoma 8 cuticle 9 guard cell 10 water

11 guard cells 12 chloroplasts 13 air spaces 14 gas exchange 15 guard cells

16 Xylem 17 Phloem 18 stoma 19 dissolve 20 air space

21 surface area 22 air spaces 23 Moist 24 dissolve 25 stomata

26 guard cells 27 stomata 28 lenticels 29 cuticle 30 oxygen

31 carbon dioxide 32 carbon dioxide 33 oxygen 34 Respiration 35 photosynthesis

36 higher 37 uptake 38 release 39 Photosynthesis 40 respiration

41 uptake 42 release 43 respiration 44 constant 45 compensation point

46 equal 47 higher 48 photosynthesis

Documents

Class: Name: Date: 9 Nutrition and gas exchange in plantsbio662.dyndns.info/DSE/WS/ws_ch09_e.pdf · 26 guard cells 27 stomata 28 lenticels 29 cuticle 30 oxygen 31 carbon dioxide 32