SB6

Question 1

What is the word equation for Photosynthesis

Answer 1

carbon dioxide + water → glucose + oxygen
uses light energy to react water and co2

Question 2

What kind of reaction is photosynthesis

Answer 2

Endothermic
energy enters from the surrounding via light energy

Question 3

How is temperature a factor of photosynthesis
(describe there relation)

Answer 3

Temperature - With an increase in temperature, the rate of photosynthesis
- if temp is too high enzymes will denature and the rate of photosynthesis wills low down

Question 4

How is light intensity a factor of photosynthesis
(describe there relation)

Answer 4

Light Intensity - For most plants the higher the light intensity the faster the rate of reaction

• until something else become the limiting factor

Question 5

How is Carbon dioxide concentration a factor of photosynthesis?
(describe there relation)

Answer 5

Carbon dioxide concentration - As the concentration of co2 increases so does the rate of reaction

• until something else become the limiting factor

Question 6

What are photosynthetic organisms the main producer’s of?

Answer 6

• make there own food
• which is biomass
• they are producers

Question 7

What is a limiting factor

Answer 7

variables that limit the rate of reaction in a chemical reaction

Question 8

What is the inverse square law

Answer 8

• light intensity ⍺ 1/distance²
• L(New) = (L(orig) x D^2(orig) / D^2(new)

Question 9

explain light intensity ⍺ 1/distance²

Answer 9

if you increase the distance from a light source, the light intensity increases

decrease the distance from the light source, increase the light intensity

Question 10

What is the function of a root hair cell

Answer 10

• found on the outer surface of roots
• used to collect water and mineral ions via osmosis

Question 11

how are water and mineral ions taken in by root hair cells

Answer 11

water - osmosis - takes no energy

mineral ions - active transport - uses energy

Question 12

how the structure of the root hair cells is adapted to absorb water and mineral ions

Answer 12

• a large surface area to allow more water and mineral ions to be absorbed quickly
• thin cell walls
  which allow for less diffusion distance making the osmosis much quicker

more mitochondria
energy to absorb mineral ion via active transport

Question 13

What is transpiration and how does it occur?

Answer 13

• It is the process of water and mineral ions flowing into a root, up the stem and out of the leaves
• Occurs through xylem vessels, which are an unbroken chain of dead cells, by which water flows up due to weak forces of attraction between water molecules
• Water then evaporates from the xylem vessels in the leaves

Question 14

What is translocation and how does it occur?

Answer 14

• This is the process of transporting sucrose to the entire plant
• It is done through companion cells pumping sucrose solution into our out of sieve cells, the increase pressure causing the sucrose to flow

Question 15

How is a xylem adapted to take water to the leaves of the plant

Answer 15

• Upon formation, a chemical called lignin is deposited which cause the cells to die
• We say that these dead cells have become lignified
• They become hollow and are joined end to end to form a continuous tube so water and mineral ions can move through
• Lignin is deposited in spirals which helps the cells withstand the pressure of from the movement of water

Question 16

How is a phloem adapted to transporting sucrose around the plant?

Answer 16

• Contain companion cells, which continuously pump sucrose in or out of sieve cells
• Sieve tube, which contains pores for sucrose solution to be pumped
• Holes in the end of cell walls allow liquids to flow from one sieve cell to the next
• Small amount of cytoplasm, so there’s more space for liquids

Question 17

What is a stomata and how does it aid gas exchange?

Answer 17

• Open pore in a leaf, that allow gases to diffuse into or out of them
• They are controlled by guard cells, which open and close them
• During the daytime, water flows into the guard cells, allowing them to be rigid and open the stomata, for gas to exchange and photosynthesis to occur whilst it’s light
• At night, water flows out of the guard cells, resulting in them losing rigidity and so the stomata shuts, to prevent excess water loss

Question 18

Why do leaves often have a large surface area?

Answer 18

• So they contain more chloroplasts, for more light energy to be trapped by chlorophyll
• This increases rate of photosynthesis

Question 19

Why are leaves thin?

Answer 19

• Reduces distance that gas has to diffuse, increasing rate of photosynthesis

Question 20

Why are there irregularly shaped spongy cells in a leaf?

Answer 20

• Creates air spaces, helping to allow gases to easily diffuse inside

Question 21

What is the role of the epidermis cells?

Answer 21

• Hold the leaf together and protect cells inside
• Transparent, to allow light o pass through for photosynthesis

Question 22

What is the role of a waxy cuticle?

Answer 22

• Helps to prevent water loss, as well as stops microorganisms entering leaf

Question 23

How does wind affect rate of transpiration?

Answer 23

• Increases
• Moves water molecules away from stomata

Question 24

How does low humidity affect rate of transpiration?

Answer 24

• Increases
• Less water vapour in air

Question 25

How does high temperatures affect rate of transpiration?

Answer 25

• Increases
• Particles have more energy, so diffuse faster

Question 26

How does greater light intensity affect rate of transpiration?

Answer 26

• Increases
• Makes stomata wider

Question 27

How are conifers adapted to cold weather?

Answer 27

• Needle-shaped, with a smaller surface area and very thick cuticle to reduce water loss
• Shape reduces wind resistance
• Shape also means they collect less snow

Question 28

• How are cacti adapted to hot weather?

Answer 28

• Hairs to trap water vapour leaving
• Spines instead of leaves, to minimise surface area. They also protect from predators
• Stomata open at night
• Thick cuticle
• Shallow, wide roots to absorb water as soon as it rains

Question 29

What is phototropism?

Answer 29

• Response to light by growing towards or away from it
• Plant shoots are positively phototrophic, so they grow towards it
• Roots are negatively phototrophic

Question 30

What is the role of the hormone ‘auxins’ in phototropism?

Answer 30

• Produced in the tips of shoots
• Cause elongation of cells
• Move to shaded side of shoot, causing the soot to bend towards the light source

Question 31

What is gravitropism?

Answer 31

• Growth response to gravity
• In roots, positive gravitropism occurs, causing them to grow downwards
• In shoots, negative gravitropism occurs, causing it to grow upwards

Question 32

What are the role of auxins in gravitropism?

Answer 32

• In shoots, they move downwards by gravity, increase cell elongation upwards
• In roots, they are pulled downwards by gravity and inhibit cell elongation upwards

Question 33

What are the commercial uses of auxins?

Answer 33

• Weed killers, by causing uncontrollable growth in broad-leaved plants
• Rooting powders, allowing roots to develop quickly

Question 34

What are the commercial uses of gibberellins?

Answer 34

• Artificially germinate
• Sprayed to overcome phototropism, to force plants to produce flowers
• Prevents seed formation when sprayed, to produce seedless fruits
• Produces bigger fruits

Question 35

What are the commercial uses of ethene?

Answer 35

• Transported when unripe, before being ripened when needed using ethene gas