plant tissues and organs

Question 1

function of xylem

Answer 1

non living transport tissue in plants which transports water and dissolved minerals from soil to roots to leaves

Question 2

function of phloem

Answer 2

living transport tissue in plants which carries sugars and amino acids from the leaves to the rest of the plant

Question 3

function of epidermis

Answer 3

outder layer of cells in a plant which protect against dehydration

Question 4

function of palisade mesophyll

Answer 4

layers of rectangular shaped cells packed full of chloroplast which carry out photosynthesis

Question 5

function of meristem

Answer 5

rapidly dividing, undifferentiated cells found in growing regions of stems and roots. it differentiates to form other types of cells needed

Question 6

function of spongy mesophyll

Answer 6

plant tissue with rounded cells, creating air spaces and a large surface area to facilitate the diffusion and exchange of gases

Question 7

what does the xylem transport

Answer 7

water and dissolved minerals

Question 8

what does the phloem transport

Answer 8

sugar and amino acids

Question 9

function of roots

Answer 9

take up water and mineral ions
anchor the plant

Question 10

function of stem

Answer 10

transports sugars, water and minerals through vascular bundles
supports leaves and flowers

Question 11

function of leaf

Answer 11

absorb sunlight and carry out photosynthesis

Question 12

function of flowers

Answer 12

reproductive organs which allow a plant to produce new plants

Question 13

where is the meristem found

Answer 13

the growing tip of a plant shoot

Question 14

what is translocation

Answer 14

the process of moving dissolved sugars from the source to where they are needed in the sink, it takes place in the phloem and requires energy -> active process

Question 15

why is translocation important for plants?

Answer 15

sugars are only produced in the leaves, so they need to be transported to other parts of the plants for respiration

Question 16

properties/structure of phloem tissue

Answer 16

made up of living cells arranged end to end which develop into tubes. they have cellulose cell walls and contain very little cytoplasm. no nuclei or organelles
kept alive by companion cells

Question 17

what is the wall at the end of each cell in the phloem tissue called?

Answer 17

sieve plate which contains small pores

Question 18

what do the small pores in the sieve plate allow you to do?

Answer 18

it allows dissolved sugars to pass from one cell to the next in a long tube

Question 19

what do garden pests such as greenfly larvae feed on? and what’s the effect

Answer 19

they feed on sugars in the phloem sieve tubes by piercing it with their mouthparts. there is now less glucose for respiration which means less energy is released and less growth

Question 20

what travels in the phloem

Answer 20

sucrose (NOT GLUCOSE)

Question 21

what is the transpiration stream

Answer 21

movement of water and dissolved mineral ions from the root to the stem and leaves which takes place within the xylem vessels

Question 22

what do the walls of xylem vessles contain

Answer 22

lignin (a woody substance) which are impermeable

Question 23

why is the transport of water and mineral ions so important for plants

Answer 23

it’s needed for photosynthesis and to keep plant cells turgid which keeps the plant upright and prevents it from wilting. mineral ions contain nitrates for growth and magnesium to make chlorophyll

Question 24

compare structures of xylem and phloem

Answer 24

xylem is made up of dead cells, where as the phloem is made up of living cells. the xylem transports water and dissolved minerals in the transpiration stream, where as in the phloem, sugars are transported. transpiration in the xyelm is a passive process where as translocation in the phloem is an active process which requires energy

Question 25

what are stomatas

Answer 25

small openings found all over the lower surface of a leaf for gas exchange

Question 26

what happens when the stomata are open

Answer 26

there’s a steady loss of water from the leaf cells as it evaporates into the internal air space then diffuses out through the stomata

Question 27

why does the stomata need to be open during the day

Answer 27

to allow carbon dioxide to diffuse in for photosynthesis

Question 28

why are the stomata closed during night

Answer 28

as there is no sunlight for photosynthesis, so it closes it and reduces the water lost

Question 29

why is it an advantage to the plant to open the stomata when light intensity is high

Answer 29

because carbon dioxide can diffuse in whilst it absorbs sunlight, allowing it to carry out photosynthesis

Question 30

suggest how the movement of potassium ions into the guard cells causes the stomata to opene

Answer 30

as potassium diffuses into the guard cells, it means the water potential is lower, which causes water to fill the guard cell via osmosis which makes the cells swell and bend open

Question 31

why is having a lot of stomata a disadvantage to a plant

Answer 31

a lot of water can be lost, causing the plant to wilt

Question 32

very little water was lost when the lower surfaces of the leaves were covered in grease, explain why

Answer 32

this is because there are more stomata on the lower surface of the leaf. Since the grease is blocking it, less water can evaporate and get out

Question 33

explain how mineral ions move from root hair cells to the leaves

Answer 33

the mineral ions are dissolved in water, which travel up the xylem in the plant, and up the stem because of transpirational pull

Question 34

which two factors increase the rate of movement of mineral ions through the plant

Answer 34

a decrease in the concentration of water vapour in the air
an increase in light intensity causing guard cells to curve/bend more

Question 35

Potometre required practical:
student repeated investigation but placed the potometre next to a fan blowing air over the leafy shoot
suggest how results would be different

Answer 35

increased of uptake, so there’s more transpiration. higher the air movement, the higher the rate of transpiration

Question 36

MASS Potometre required practical:
whats the purpose of the polyethene bag wrapped around the plant pot

Answer 36

stops water from evaporating and contributing to the numbers on the scale`

Question 37

design an experiment using the mass potometre to investigate the effect of changing one of: Light intensity, temperature, humidity or airmovement on the rate of transpiration on a leafy shoot

Answer 37

first place 12 plants which are the same species, with a plastic bag around the whole pot each on a mass potometer. place 4 plants in a dim lit room, 4 in a bright room and 4 in a dark room. measure starting mass for all the plants and leave them in their rooms for half an hour. after, record the final mass of each plant and calculate the percentage change of each plant and work out the mean percentage change for the plants in each light intensity

Question 38

explain why there is more stomata on the lower side of the leaf

Answer 38

on the lower side of the leaf, there’s more shade which reduces evaporation and prevents excessive water loss

Question 39

describe how water is transported from the soil to the atmosphere through a plant

Answer 39

the root hair cells absorb the water from the soil via osmosis
the water travels through the xylem vessles to the leaves, caused by transpirational pull where it is lost through the stomata to the atmosphere where it evaporates