Plant organisation

Question 1

Waxy cuticle

Answer 1

Reduces evaporation from the surface of the leaf
Helps prevent the leaf from drying out

Question 2

Upper and lower epidermis

Answer 2

Protects surface of the leaf
Upper is transparent that allows light to pass through for photosynthesis
Lower epidermis has stomata - controls water vapour levels

Question 3

Palisade cells

Answer 3

Packed full of chloroplasts, where photosynthesis occurs
As chlorophyll absorbs sunlight

Question 4

Spongy mesophyll

Answer 4

Air spaces to allow carbon dioxide to diffuse from the stomata through the spongy mesophyll so it can reach palisade cells for photosynthesis
Allows oxygen to diffuse through the spongy mesophyll to the stomata

Question 5

Stomata

Answer 5

Allows carbon dioxide to enter and oxygen to leave the leaf
Also controls amount of water vapour to pass out of the leaf by osmosis
As there’s a high concentration of water inside than outside leaf

Question 6

Guard cells

Answer 6

Opens and closes stomata to control water vapour loss

Question 7

Xylem

Answer 7

Made up of dead cells with lignin
Transports water and minerals from the roots to stem and leaf
Dissolved mineral ions (Mg+ ions) to make chlorophyll
Water for photosynthesis

Question 8

Phloem

Answer 8

Transports products of photosynthesis to where it is needed ie sucrose and amino acids. This is translocation
Can be used for respiration
Store east starch

Question 9

Adaptation: Large surface area

Answer 9

Absorbs more light

Question 10

Adaptation: Network of veins

Answer 10

To support the leaf and transport water, mineral ions and sucrose

Question 11

Adaptation: Thin

Answer 11

Shorter diffusion distance

Question 12

Epidermal tissue

Answer 12

Made of epidermal cells at the top and bottom
Cover the leaf to protect the surface

Question 13

Translocation

Answer 13

Movement of sugars through the phloem tissue

Question 14

Meristem tissue

Answer 14

At growing tips such as shoots/roots
Contain stem cells that can differentiate into any different type of cell

Question 15

Transpiration

Answer 15

When water vapour evaporated from surface of the leaves because the plant takes in too much water at a given time for photosynthesis to remove excess

Question 16

Stages of transpiration stream

Answer 16

Water vapour in the palisade evaporate inside to be vapour Then diffuses through air spaces in spongy mesophyll
Out the leaf
Water in the xylem passes into the leaf to replace lost water
More water from soil into root hair cell up the xylem to the leaf

Question 17

Why do we need transpiration?

Answer 17

Brings water to the leaf for photosynthesis
Transports dissolved magnesium ions in water to the leaf for minerals
Cools plant down in warm weather

Question 18

How does temp affect transpiration?

Answer 18

Higher temp = higher rate of transpiration
Higher temp means evaporation is faster

Question 19

How does humidity affect transpiration?

Answer 19

Dryer conditions = higher rate of transpiration
Evaporation quicker under dry conditions
As there is a higher concentration of water molecules in cell than in air = higher concentration gradient

Question 20

How does the wind effect transpiration?

Answer 20

More wind = higher rate of transpiration
More wind removes water vapour
More water to evaporate

Question 21

How does light intensity affect rate of transpiration?

Answer 21

More light = higher rate of transpiration
More light means more photosynthesis
Which causes the stomata to open and let CO2 in, meaning water vapour can pass out more

Question 22

How does a stomata/guard cells work in high light conditions?

Answer 22

Guard cells swell and change shape to open stomata
CO2 can diffuse in for photosynthesis

Question 23

How does a stomata/guard cell work in dryer/ hot conditions?

Answer 23

Guard cells change shape to close stomata
To reduce water loss through transpiration once enough cooling has happened
Saves water since it’s dry
However plant can’t photosynthesis

Question 24

Use of glucose (c)?

Answer 24

Forms cellulose which strengthens plant cell wall

Question 25

Use of glucose (s)?

Answer 25

Forms starch which is the storage form of glucose
Glucose is soluble in water and so will disrupt transport of water
Therefore converted into insoluble starch

Question 26

Use of glucose (a)?

Answer 26

Join with nitrate ions to form amino acids
To synthesise proteins