Transport, Storage And Gas Exchange In Flowering Plants

Question 1

Autotroph

Answer 1

Organism that makes its own food

Question 2

Metabolism

Answer 2

Sum of all chemical reactions in an organism

Question 3

Transpiration

Answer 3

Loss of water vapour from aerial parts of plant by evaporation

Question 4

Diffusion

Answer 4

The movement of molecules from a region of high concentration to a region of low concentration

Question 5

Osmosis

Answer 5

The moment of water across a semi permeable membrane from an area of high water concentration to low concentration

Question 6

Passive transport

Answer 6

Does not require energy

eg osmosis

Question 7

Active transport

Answer 7

Does require energy

Question 8

Why Plants need a transport system

Answer 8

To provide the materials needed for various plant metabolic processes:

Photosynthesis: CO2 taken in from atmosphere, water from roots
Respiration: 02 used from photosynthesis
Reproduction and growth

Question 9

Materials transported by plants

Answer 9

Water
Minerals ( nitrates & phosphates by diffusion and active transport)
Carbon dioxide
Carbohydrates ( glucose from photosynthesis, transported through phloem, stored as starch in the leaf or used in respiration)@

Question 10

Leaf adaptations for photosynthesis

Answer 10

Flat (large surface area)
Large number of chloroplasts present ( mostly on the palisade layer)
Contains stomata

Question 11

Leaf structure

Answer 11

Stomata 
Epidermis 
Vascular bundle 
Ground tissue 
Guard cells

Question 12

Stomata

Answer 12

What : small pores on underside of leaves
Location: undersides of leaves
Function: gas exchange- co2 in, o2 and water vapour out
Adaptations/features: large numbers= large surface area for gas exchange

Question 13

Epidermis

Answer 13

Composition/derived from: dermal tissue

Function: protection

Question 14

Vascular bundle

Answer 14

Composition: xylem + phloem
Function: transport of water, minerals and food

Question 15

Ground tissue

Answer 15

Function: food storage, photosynthesis

Palisade layer: contains more chloroplasts so more photosynthesis occurs here as it is closer to sunlight

Question 16

Guard cells

Answer 16

Function: control opening and closing of stomata
How: swell/ become turgid due to high concentration of water/guard cells open/ become flaccid/ shrink when water lost/ guard cells close

Question 17

Sources of carbon dioxide

Answer 17

From the atmosphere, diffuse into stomata

Product of respiration

Question 18

How intake of co2 is controlled

Answer 18

Stomata opening and closing

Day: OPEN (water vapour out and co2 in when photosynthesis is occurring)
Night: CLOSED ( stomata closed, reducing water loss and co2 intake, photosynthesis not occurring)

Question 19

High levels of co2

Answer 19

Stomata close- no more needed for photosynthesis

Question 20

Low levels of co2

Answer 20

Stomata open- more needed for photosynthesis

Question 21

Why do the stomata close sometimes during the day?

Answer 21

If the plant has lost too much water by evaporation

If temperatures are too high

Question 22

By closing stomata….

Answer 22

Plant reduces water loss

Question 23

How water enters root hairs to vascular tissue

Answer 23

Water enters the root hair cells by osmosis - through a selectively permeable membrane
Cytoplasm of root hair cells has a higher solute concentration than the water in soil
Water moves from cell to cell by osmosis

Question 24

Adaptations of root hairs

Answer 24

Walls only one cell thick

Large numbers=> large surface area for absorption

Question 25

Methods of transport through roots

Answer 25

Osmosis -> from soil to root hair cells

Diffusion -> from root hair cells to root cells (across tissues)

Question 26

How water reaches great heights

Answer 26

Root pressure

Transpiration

Question 27

Root pressure

Answer 27

Build up of water in the root cells creates pressure pushing water upwards

Question 28

Transpiration outline

Answer 28

Water evaporates from stomata and diffuses into atmosphere
As water diffuses from the leaf it pulls more water out of the leaf
Osmotic gradient created: lower water concentration in leaves
Water moves from xylem to leaf cells

Question 29

Why control transpiration

Answer 29

Prevents wilting (high transpiration rate will cause plant to wilt)

Question 30

How to control transpiration

Answer 30

Leaves have a waxy cuticle - water cannot pass through
Stomata location- lower surface area of the leaf where less evaporation occurs
Guard cells - control shape of stomata open and close

Question 31

Movement of water through the xylem

Answer 31

How: cohension-tension model
What: explains movement of water against the force of gravity
Who: Henry Dixon and John Joly

Question 32

Cohesion tension model

Answer 32

Cohesion- water molecules stick to each other due to hydrogen
Adhesion- water adheres to the walls of xylem
Cohesive forces stronger than adhesive forces
As each water molecule evaporates(or by transpiration) more water is pulled up through xylem(strong cohesion between water molecules and adhesion between water and walls)
Water in xylem vessels now under tension which ensures water movement - xylem stretches and becomes narrow
A continuous stream of water is now moving
This tension is great enough to pull water to great heights

Question 33

Daylight

Answer 33

Stomata open: transpiration occurs

Question 34

Nighttime

Answer 34

Transpiration stops : tension is released, xylem vessels return to normal width

Question 35

Adaptation of xylem for transpiration

Answer 35

Lignified

Continuous and narrow lumen with no cell contents

Question 36

Modified storage organs

Answer 36

Plant organs that are modified and used to store food as starch/sucrose/cellulose

Question 37

Examples of modified storage organs

Answer 37

Modified root: tap root eg carrot
Modified stem: potato tuber
Modified leaf: tulip, onion (produce bulbs)