Unit 2: Organisation - Plant Tissues, Organs, and Organ Systems

Question 1

how do specialised plant cells get formed?

Answer 1

they are formed from a process called differentiation

Question 2

draw and label a diagram of a root hair cell

Answer 2

Question 3

what is the function of a root hair cell

Answer 3

1. they help to absorb water by osmosis
2. they absorb mineral ions by active transport and diffusion

Question 4

what are the adaptations of a root hair cell

Answer 4

1. Root hair - increases surface area for osmosis and diffusion of mineral ions
2. Thin cell wall - short diffusion distance
3. Vacuole - contains cell sap which gives cell low water concentration (maintains gradient for osmosis)

Question 5

draw and label a diagram of a xylem cell

Answer 5

Question 6

what is the function of a xylem cell

Answer 6

1. transports water + mineral ions
2. UP the plant, roots to shoots/leaves
3. via the TRANSPIRATION STREAM

Question 7

what are the adaptations of a xylem cell

Answer 7

1. the cells are dead and hollow (empty)
2. cells are elongated
3. cell walls are strengthened by lignin

Question 8

draw and label a diagram of a phloem cell

Answer 8

Question 9

what is the function of a phloem cell

Answer 9

1. transports sugar solution
2. UP and DOWN plant (bidirectional)
3. via TRANSLOCATION

Question 10

what are the adaptations of a phloem cell

Answer 10

1. cells are living (sugars move by active transport)
2. sieve plate (pores) allow sugar solution to move from cell to cell
3. cells are elongated

Question 11

what do epidermal tissues do

Answer 11

they cover the plant

Question 12

what does the palisade mesophyll do

Answer 12

it is the main site of photosynthesis

Question 13

what does the spongy mesophyll do

Answer 13

it has air spaces for diffusion of gases and some photosynthesis

Question 14

what do the xylem and phloem do

Answer 14

they transport substances around the plant

Question 15

where is meristem tissue found

Answer 15

at growing tips of shoots and roots

Question 16

what happens in the meristem tissue

Answer 16

cells divide by mitosis and then differentiate into specialised cells

Question 17

what is the cuticle

Answer 17

a layer of wax (not a tissue)

Question 18

draw and label a diagram of leaf

Answer 18

Question 19

give an example of a plant organ

Answer 19

vascular system

Question 20

what is the vascular system made up of

Answer 20

phloem tissue and xylem tissue

Question 21

How is water absorbed?

Answer 21

It is absorbed by osmosis from the soil.

Question 22

definition of transpiration

Answer 22

the loss of water vapour from the surface of plant leaves

Question 23

how does transpiration occur

Answer 23

water vapour is mainly lost via open stomata
some get lost via cuticle

Question 24

draw a diagram of an open and closed guard cell

Answer 24

Question 25

when is the stoma opened

Answer 25

in daylight

Question 26

when is the stoma closed

Answer 26

at night (no transpiration occurs)

Question 27

describe the mechanism of stomatal opening during the day

Answer 27

The rate of transpiration is highest during the day The active transport of H+ ions causes the stomata to open The absoption of K+ ions cause the guard cells to need more water as it lowers its water potential Water is transferred to guard cells from nearby cells via osmosis The uneven thickening of cellulose lets the cells change shape The guard cells bow and form an opening When the stomatal openings are largest, it is known as 'turgid'

Question 28

what is a bubble potometer used for

Answer 28

to measure the rate of transpiration

Question 29

describe how the potometer is used to measure the rate of transpiration

Answer 29

When water is transpired from the leaves, the shoot absorbs water from the potometer The distance the air bubble moves in a certain period of time can be used to calculate the rate of water uptake. The apparatus can be reset - to investigate the effect of a different environmental factor

Question 30

What are some benefits of using a potometer

Answer 30

it is set up underwater to avoid air bubbles the junction at shoot is sealed with vaseline to prevent air leaks the reservoir allows appartus to be reset.

Question 31

why is the capillary of the potometer narrow

Answer 31

1. easier to see bubble move 2. bubble will move further

Question 32

formula for rate of transpiration

Answer 32

cross sectional area of capillary tube x distance travelled by the bubble = volume of water lost.

Question 33

what factors affect the rate of transpiration

Answer 33

temperature humidity air movement light intensity

Question 34

what is the assumption for potometer

Answer 34

the water uptake = water lost in transpiration

Question 35

Describe wilting

Answer 35

The plant does not have enough water, as all the water has been transpired The rate of water loss > water uptake Plant cells have lost turgor pressure (they are now flaccid) The plant cells are plasmolysed, they can no longer support the plant.

Question 36

as temp increases, the rate of transpiration _____

Answer 36

increases

Question 37

explain how temperature affects the rate of transpiration

Answer 37

As the temperature increases, the kinetic energy of the water molecules increases. This increases the rate of evaporation. This increases the rate of diffusion of water vapour out of the leaf

Question 38

as humidity increases, the rate of transpiration _________

Answer 38

decreases

Question 39

explain how humidity affects the rate of transpiration

Answer 39

More humid air = more water vapour present (so smaller gradient for diffusion) Increasing humidity increases the concentration gradient between the inside and the outside of the leaf. This decreases the rate of diffusion, and therefore the rate of transpiration decreases.

Question 40

as air movement increases, the rate of transpiration __________

Answer 40

increases

Question 41

explain how air movement affects the rate of transporation

Answer 41

Air movement blows away the diffusion shell around the leaf. This increases/maintains the diffusion gradient.

Question 42

as light intensity increases, the rate of transpiration __________

Answer 42

increases

Question 43

explain how light intensity affects the rate of transporation

Answer 43

As light intensity increases, the rate of photosynthesis increases. There is more stomata open for gas exchange (CO2 into the leaf) This increases the rate of diffusion

Question 44

which part of the leaf usually has the most stomata

Answer 44

on the lower surface the leaf

Question 45

rate of transpiration increases when:

Answer 45

- temp increases - air movement increases - light intensity increases - humidity decreases - more stomata (stomata density) - more leaves/ bigger leaves