topic 6: plant structures and their functions

Question 1

what are the 4 limiting factors of photosynthesis

Answer 1

carbon dioxide levels
light intensity
temperature
amount of plant chlorophyll

Question 2

equipment needed for core practical topic 6

Answer 2

.ruler
.light source
.sodium hydrogen carbonate solution (carbon dioxide for photosynthesis)
.pondweed (cut end at the top)
.funnel and measuring cylinder with water to measure oxygen volume

Question 3

relationship between the mean number of bubbles per minute and the distance from the light source

Answer 3

inverse-square law
.doubling the distance cause light to fall by four times

Question 4

what increase the rate of transpiration

Answer 4

.higher temperatures
.dryer conditions
.windier conditions
.light intensity (increases rate of photosynthesis)

Question 5

How do green houses help to increase crop yield

Answer 5

Farmers light heat and add extra carbon dioxide into green houses to improve crop yield Cependant

some gardeners use oil burners as these increase heat and carbon dioxide simultaneously

Question 6

how do the stomata function

Answer 6

.surrounded by two guard cells
.when light intensity is high/ daytime, the guard cells swell and change shape
.this causes stomata to be opened and allow co2 in for photosynthesis by diffusion

.in hot conditions the stomata is closed to reduce loss of water through transpiration
.plant then cannot photosynthesise

Question 7

explain phototropism with auxins

Answer 7

.auxin if produced at the tip of the plant shoot
.in shoots auxins trigger cells growth/division
.light causes auxins to concentrate on the darker side of the plant shoot
.auxins spread down the shoot so cells grow faster on the darker side
.causes the shoot to grow towards the side with the light

Question 8

auxins in gravitropism/geotropism

Answer 8

.auxin is produced in the roots
.auxins inhibit cell growth in the plant roots
.gravity causes auxins to concentrate on the lower side of the root
.auxins cause the lower side to grow slower than the upper side
.this causes the roots to grow towards the force of gravity

Question 9

role of gibberellins in plants (simple)

Answer 9

important in starting the germination of seeds#

Question 10

role of ethene in plants (easy)

Answer 10

controls cell division and ripening of fruits

Question 11

uses of auxins

Answer 11

.rooting powder to clone plants
.weedkillers

Question 12

uses of gibberellins in agriculture

Answer 12

.early germination of plants
.encourage plants to flower
.be used to make fruit grow larger

Question 13

uses of ethene in agriculture

Answer 13

.trigger fruits to ripen to reduce damaged product during transportation

Question 14

how to calculate light intensity

Answer 14

light intensity = light/distance squared

Question 15

features of the xylem

Answer 15

.made of dead cells (so water isn’t used)
.cell walls break down
.lignin to provide extra support

Question 16

describe the transpiration stream

Answer 16

.water enters into the roots through osmosis
.water moves up the plant through the xylem to leaves
.once the water is used for photosynthesis it exits through pores in the leaf
.this constant need to replenish water leads to the constant stream

Question 17

why will transpiration happen more when its lighter

Answer 17

more photosynthesis will occur causing more need to replenish water used in reaction

Question 18

why will transpiration happen more when it is dry

Answer 18

evaporation of water out the leaf cause more water to be delivered to the leaf through the transpiration stream

Question 19

why will transpiration happen more when windy

Answer 19

wind pushes more water from out the leaves so more water is needed

Question 20

what do phloem transport

Answer 20

sugars and mineral ions

Question 21

how is the phloem designed for function

Answer 21

.substances can travel in both directions as all parts of the plant require sugars
.phloem cells are living
.has companion cells with lots of mitochondria to keep the phloem cells alive
.sieve cells allow the sugars to pass through

Question 22

what process is the phloem involved in

Answer 22

translocation

Question 23

role of waxy cuticle

Answer 23

physical barrier for plants protection

Question 24

upper epidermis trait

Answer 24

see through to allow light

Question 25

role of palisade cells

Answer 25

contains mans chloroplasts for photosynthesis

Question 26

role of spongy mesophyll

Answer 26

where gases diffuse

Question 27

role of stomata and guard cells

Answer 27

allow for diffusion of gases into and out of the cell
transpiration of water out of the leaf

Question 28

explain why potato chips lost mass in salt solution

Answer 28

there is a high concentration of sodium chloride concentration outside the cell than inside

water moves out the potato through osmosis

into the solution

Question 29

what can plants make out of glucose

Answer 29

cellulose-what the cell wall is made of strengthens the cell structure

Question 30

what are the 5 uses for glucose in plants

Answer 30

Cellular respiration - break down the glucose to release energy

Make cellulose - which is used to make strong cell walls

Make starch - which is used to store glucose for a later time

Make amino acids - which are used to make proteins

Make lipids - these store the energy as fats or oils for later use

Question 31

term when the graph levels off when mapping some limiting factors

Answer 31

plateaud

Question 32

describe changes in rate of photosynthesis due to temperature

Answer 32

Rate initially increases with temperature as particles have more energy and move faster, so react more frequently

Highest rate is at optimum temperature for enzyme

At higher temperatures the rate decreases as bonds holding the enzyme together begin to break, and so the enzyme changes shape

Rate falls to zero as enzymes denature

Question 33

what do farmers use in greenhouses to climatize and why

Answer 33

paraffin heaters increase temperature and carbon dioxide volume

Question 34

how do auxins act as weedkillers

Answer 34

Stimulates too much growth

Disrupts growth process and so kills the plant