adaptations of plants to water

Question 1

difference between hydrophyte and xerophyte

Answer 1

hydrophytes are plants adapted to live in water or where the ground is very wet and xerophytes are plants adapted to live in dry conditions

Question 2

what are mesophytes

Answer 2

they are able to take up sufficient water to replace transpiration (most plants)

Question 3

what are hydrophytes

Answer 3

they live either partially or completely submerged in water - have problems with oxygen uptake

Question 4

what are xerophytes

Answer 4

they live in areas where lost by transpiration is greater than taken up by roots

Question 5

what happens to plants on land

Answer 5

the stomata is open during the day so gas exchange can occur. this means water is also lost.

Question 6

what are the adaptations of plants living on land

Answer 6

• reduce loss of water and to replace water that is lost

Question 7

how do terrestrial plants reduce water loss

Answer 7

by structural and behavioural adaptations

Question 8

function of waxy cuticle

Answer 8

a waxy cuticle on the leaf reduces water loss due to evaporation through the epidermis

Question 9

what do the stomata on the underside of the leaf do

Answer 9

reduce evaporation from the direct heat of the sun

Question 10

why are most stomata closed at night

Answer 10

theres no light for photosynthesis

Question 11

what do deciduous plants do

Answer 11

lose leaves in the winter when the ground may be frozen and when temperatures are too low for photosynthesis

Question 12

plants with structural and physiological adaptations enabling them to survive in hot and dry conditions are..

Answer 12

..xerophytes

Question 13

examples of xerophytes

Answer 13

cacti, conifers and marram grass

Question 14

what is marram grass

Answer 14

plant found widely on sand dunes and coastal areas in dry and salty conditions

Question 15

what about plants that survive in cold and icy conditions

Answer 15

they are also xerophytes

Question 16

adaptations of xerophytes

Answer 16

• thick waxy cuticle
• sunken stomata
• reduced number of stomata
• reduce leaves
• hairy leaves
• curled leaves
• succulents
• leaf loss
• root adaptations

Question 17

why do xerophytes have a thick waxy cuticle

Answer 17

minimise water loss. common in evergreen plants helping them to survive both hot, dry summers and cold winters when water can be hard to absorb from the frozen ground. e.g. holly

Question 18

why do xerophytes have sunken stomata

Answer 18

located in pits which reduce air movement producing microclimate of still humid air that reduces the water potential gradient and reduces transpiration e.g. marram grass, cacti and conifers

Question 19

why do xerophytes have reduced number of stomata

Answer 19

reduce water loss by transpiration and limits gas exchange

Question 20

why do xerophytes have reduced leaves

Answer 20

reduces water loss. conifer leaves are reduced to thin needles. reduces surface minimising water loss by transpiration

Question 21

why do xerophytes have hairy stems

Answer 21

create microclimate of still humid air reducing the water potential gradient and minimising water loss by transpiration from surface of leaf. marram grass has microhairs in the sunken stomatal pits

Question 22

why do xerophytes have curled leaves

Answer 22

confines all the stomata within a microenvironment of still humid air reducing diffusion of water vapour from the stomata e.g. marram grass

Question 23

what do succulents do (x)

Answer 23

store water in specialised parenchyma in their tissues and roots. have swollen or fleshy appearance. water is stored when in plentiful supply and used in droughts. e.g. desert cacti, aloe vera

Question 24

why do xerophytes lose their leaves

Answer 24

prevents water loss. trunks and branches turn green and photosynthesise with minimal water loss to keep it alive

Question 25

what are the root adaptations of xerophytes

Answer 25

long tap roots growing deep into the ground can penetrate several metres so they can access water that is a long way below the surface. a mass of widespread shallow roots with a large SA to absorb any water before evaporation e.g. cacti, marram grass

Question 26

how do xerophytes avoid the problems of low water availability

Answer 26

plants may lose their leaves and become dormant or die completely leaving seeds behind to germinate and grow rapidly when rain falls again. others survive as storage organs such as bulbs, corns and tubers. few plants can withstand complete dehydration and recover. they appear dead but when it rains the cells recover the plants become turgid and green and photosynthesise

Question 27

what does trehalose do

Answer 27

enables xerophytes cells to survive unharmed

Question 28

why do xerophytes leaves have low surface area

Answer 28

for slower diffusion and so reduce evaporation of water

Question 29

where do marram grass live

Answer 29

lives on sand dunes. any water in the sand drains away quickly, the sand is salty, leaves exposed to dry conditions

Question 30

adaptations of marram grass

Answer 30

- outer epidermis = small thick walled cells (thick cuticle no stomata) to reduce evaporation - hairs stop water vapour reducing the water potential gradient between the leaf and the air - stomata in pits to trap air with moisture close to the openings (folded and covered by hairs) - hinge (bulliform) cells lose turgidity and collapse in dry conditions causing the leaf to roll up (traps air reducing water loss)

Question 31

what is a succulent

Answer 31

having thick fleshy leaves or stems adapted to storing water.

Question 32

adaptations of cacti

Answer 32

cactis are succulents - they store water in their stems to become fleshy or swollen. - stem is ribbed or fluted so it can expand when water is available - leaves are reduced to spines which reduces surface area and water loss - stem is green - has widespread roots

Question 33

plants that live in water and require adaptations to cope with growing in water or permanently saturated soil are..

Answer 33

..hydrophytes

Question 34

what must the leaves of hydrophytes do

Answer 34

leaves must float on the surface as water logging is a problem

Question 35

what must the air spaces of hydrophytes be filled with

Answer 35

air not water

Question 36

give an example of a hydrophyte

Answer 36

water lillies

Question 37

adaptations of hydrophytes

Answer 37

- very thin or no waxy cuticle - many always open stomata on upper surfaces - reduced structure to the plant - wide flat leaves - small roots - large surface area of stems and roots under water - air sacs - aerenchyma

Question 38

why do hydrophytes have a very thin waxy cuticle

Answer 38

dont need to conserve water. water loss isnt an issue

Question 39

why do hydrophtes need many open stomata on upper surface

Answer 39

maximising number of stomata maximises gas exchange. no risk to the plants loss of turgor as water is always available. guard cells are inactive. stomata need to be in contact with the air

Question 40

why do hydrophytes have a reduced structure

Answer 40

water supports the leaves and slowers so there no need for strong supporting structures

Question 41

why do hydrophytes have wide flat leaves

Answer 41

they spread across the surface of the water to capture as much light as possible

Question 42

why do hydrophytes have small roots

Answer 42

water can diffuse directly into stem and leaf tissue so there is less need for uptake by roots

Question 43

why do the stems and roots of hydrophytes have a large surface area under water

Answer 43

maximises area for photosynthesis and for oxygen to diffuse into submerged plants

Question 44

why do hydrophytes have air sacs

Answer 44

enables leaves to float to the surface of the water

Question 45

what are aerenchyma

Answer 45

specialised parenchyma tissue that forms in the leaves, stems and roots. they have many large air spaces formed by apoptosis in normal parenchyma

Question 46

what is apoptosis

Answer 46

programmed cell death

Question 47

what is the function of aerenchyma

Answer 47

makes leaves and stems more buoyant forms low resistant internal pathway for movement of substances to tissues below water - helps plants cope with extremely low oxygen conditions

Question 48

where are aerenchyma found

Answer 48

in crop species growing under water

Question 49

what happens when there is plenty of water

Answer 49

roots become waterlogged so air is in short supply.

Question 50

what is the problem with hydrophytes

Answer 50

they dont transpire and cant transport mineral ions

Question 51

why do hydrophytes have

Answer 51

they have hydathodes which release water droplets that evaporate from the leaf surface

Question 52

what are the adaptations of water lillies

Answer 52

- many large air spaces in the leaf. keeps leaves afloat so they are in the air and absorb sunlight - stomata are on the upper epidermis so they are exposed to the air allowing gas exchange - leaf stem has many large air spaces to help with buoyancy and allows oxygen to diffuse quickly to the roots to aerobic respiration