Topic 6 - Plant structures and their functions

Question 1

define auxins

Answer 1

plant hormones that control the growth at the tips of the shoots and roots

Question 2

where does auxin promote growth and where does it inhibit growth?

Answer 2

it promotes growth in the shoot but inhibits growth in the roots

Question 3

what 2 tropics describe shoots

Answer 3

positively phototropic, negatively gravitropic

Question 4

what 2 tropics describe roots

Answer 4

positively gravitropic, negatively phototropic

Question 5

what does positive/ negative phototropic mean

Answer 5

grows towards/ away from the light

Question 6

what does positive/ negative gravitropic mean

Answer 6

grows towards/ away from gravity

Question 7

what side (shaded or exposed) are the auxins in the shoot on when exposed to light and what does this do

Answer 7

shaded side accumulates more auxin, this makes cells grow faster on the shaded side so the shoot bends towards the light

Question 8

what side (higher or lower) are the auxins in the roots on when growing sideways and what does this do

Answer 8

there is more auxin on the lower side, this inhibits growth so the root will bend downwards as the cells on top elongate faster

Question 9

when a shoot is growing sideways, what side (higher or lower) has more auxins and what will happen due to this

Answer 9

gravity produces unequal distribution of auxins, so there is more auxin on the lower side; lower side grows faster which bends the shoot upwards

Question 10

if a root starts being exposed to some light what side (shaded or exposed) will the auxins mostly be on and what will this do

Answer 10

accumulates on the shaded side, so cell elongation on the lower side causes roots to bend downwards back into the ground

Question 11

where does the main mass of trees come from?

Answer 11

from photosynthesis, where carbon dioxide becomes glucose

Question 12

where are stomata found?

Answer 12

on the underside of leaves

Question 13

what is the word equation for photosynthesis?

Answer 13

carbon dioxide + water –> glucose + oxygen

(with light and chlorophyll on the arrow)

Question 14

what is the chemical equation for photosynthesis?

Answer 14

6C02 + 6O2 –> C6H12O6 + 6H2O

Question 15

what is the role of light in photosynthesis?

Answer 15

provide energy to the reaction as it is endothermic

Question 16

What is the role of chlorophyll in photosynthesis?

Answer 16

absorbs the light energy so it can be transferred to the reaction

Question 17

what happens to the glucose in photosynthesis?

Answer 17

can be biosynthesised to make amino acids and proteins, fatty acids, starch for storage, cellulose, respiration

Question 18

what do stomata do?

Answer 18

the open in response to light and allow CO2 to diffuse into and water and oxygen to diffuse out

Question 19

what happens to the stomata when it is in the dark or in water? and why

Answer 19

the stomata will close to conserve water

Question 20

which 3 environmental factors affect the rate of photosynthesis?

Answer 20

carbon dioxide concentration
temperature
light intensity

Question 21

why is the rate of photosynthesis often limited in winter?

Answer 21

becuz there is low light intensity and temperatures

Question 22

in the photosynthesis (pondweed) practical what gas is in the bubbles?

Answer 22

oxygen

Question 23

in the photosynthesis (pondweed) practical suggest how you could change the light intensity?

Answer 23

by moving the lamp closer to the beaker containing pondweed

Question 24

in the photosynthesis (pondweed) practical suggest 3 variables to keep constant

Answer 24

volume of pondwater
mass of pondweed
type of pondweed

Question 25

why does the rate of photosynthesis fall at high temperatures? (1)

Answer 25

at high temp enzymes may get denatured

Question 26

why do enzymes denature at high temps?

Answer 26

they have so much energy that they collide into each other so much so the enzymes denature and dont function properly. photosynthesis is controlled by enzymes

Question 27

why to the graphs to show the light intensity and carbon dioxide’s effect on photosynthesis level off?

Answer 27

the other two factors become the limiting factor which limits the rate

Question 28

what is the formula to find light intensity?

Answer 28

1 / distance ^2

Question 29

why do the products of photosynthesis have more energy than the reactants of photosynthesis?

Answer 29

the thermal energy (light) is into the reaction and is transferred into chemical energy to glucose

Question 30

how does glucose make up most of biomass?

Answer 30

biosynthesis converts glucose into other molecules. these other molecules make up biomass

Question 31

what materials do plants need to transport?

Answer 31

water, glucose, oxygen, carbon dioxide, minerals

Question 32

where in the plant is glucose transported?

Answer 32

everywhere

Question 33

where in the plant is water and minerals transported?

Answer 33

from the roots upwards

Question 34

where is carbon dioxide transported?

Answer 34

out from the stomata of the leaves

Question 35

why do plants need water?

Answer 35

transpiration, its a substrate for photosynthesis, its a solvent to carry dissolved compounds around a plant, keeps cells turgid to provide support for the plant

Question 36

how does water come into a plant?

Answer 36

water comes into the root hair cells by osmosis, this is becuz there is a higher concentration inside the cell than outside

Question 37

how do minerals come into a plant?

Answer 37

minerals come into the root by active transport, they are moving against the concentration gradient so it requires energy

Question 38

how is the root hair cell adapted for absorption

Answer 38

has hair like structures to increase surface area for maximum absorption space

Question 39

why do mineral ions come into the plant?

Answer 39

they are in very low concentration in the soil, so the enter by active transport, against conc gradient, using the ATP made in respiration

Question 40

state 3 features of the xylem

Answer 40

thick cell walls
hollow tube with no cytoplasm
made of dead cells

Question 41

what is transpiration?

Answer 41

it is the evaporation of water from the leaves, driven by heat energy from the sun

Question 42

what is the role of the xylem

Answer 42

to carry water that is dissolved minerals from the roots to the stem and leaves

Question 43

what direction and what process are water and minerals ions transported

Answer 43

transported up by transpiration

Question 44

what direction and what process are sucrose and amino acids transported

Answer 44

transported down by translocation

Question 45

define guard cells

Answer 45

found on either side of stoma, they control gas exchange in leaves by controlling opening and closing the stoma

Question 46

define lignin

Answer 46

carbohydrate material lining the xylem vessels and providing strength and support

Question 47

define minerals

Answer 47

nutrient ions essential for healthy growth

Question 48

define phloem

Answer 48

vessels in plant that transport sugars

Question 49

define root epidermis

Answer 49

outer lay of cells of a root

Question 50

define root hair cells

Answer 50

specialised cells that increases the surface area of the root epidermis to improve the uptake of water and minerals

Question 51

define spongy mesophyll cells

Answer 51

plant leaf tissue with loosely packed cells and air spaces between them to allow gas exchange

Question 52

define stomata

Answer 52

tiny pores in the leaf epidermis that allow gas exchange

Question 53

define transpiration

Answer 53

evaporation of water through stomata of the leaves

Question 54

define vascular tissue

Answer 54

plant tissue consisting of phloem and xylem that transports material in a plant

Question 55

define xylem

Answer 55

narrow, dead tubes with lignin in their walls for the transport of water and minerals in plants