SB6

Question 1

What is the formula for photosynthesis

Answer 1

Carbon dioxide + Water –>(energy transferred by light) Glucose + oxygen

Question 2

Where does photosynthesis occur

Answer 2

In the chloroplasts

Palisade mesophyll

Question 3

What happens to glucose molecules after they are made

Answer 3

They link together to form a starch polymer and stay in the chloroplasts until photosynthesis stops
It’s moved into the cytoplasm and used to make surcrose

Question 4

What does sucrose do

Answer 4

It’s transported around the plant and used to make starch, other molecules for the plant (eg: cellulose) and glucose for respiration

Question 5

Name some leaf adaptations

Answer 5

• Broad and flat leaves, large surface area
• Waxy cuticle
• Palisade cells near the top (packed with chloroplasts)
• Stomata allows carbon dioxide to diffuse into leaf
• Guard cells open and close stomata (water flows into guard cells making them rigid in the light)
• Thin leaves so carbon dioxide doesn’t have to diffuse far to get to cells that need it

Question 6

What is gas exchange

Answer 6

The flow of different gases in and out across a membrane

Question 7

Name the limiting factors of photosynthesis

Answer 7

• Carbon dioxide concentration
• Temperature
• Light intensity

Question 8

What does it mean when one limiting factor doesn’t affect the rate anymore

Answer 8

Something else is a limiting factor

Or if it’s temperature, the temperature is too high

Question 9

What is the formula for a new light intensity

Answer 9

Iⁿᵉʷ=(Iᵒʳᶦᵍᶦⁿᵃˡ x d²ᵒʳᶦᵍᶦⁿᵃˡ)÷d²ⁿᵉʷ

I= light intensity
d= distance

Question 10

Why do we use inverse square law for light intensity

Answer 10

Because light intensity is inversely proportional to the new distance squared

Question 11

What are some control variable of the light intensity practical

Answer 11

• The number of algal balls

- The temperature

Question 12

How can you improve the experiment (light intensity)

Answer 12

If the bubbles are too fast, you can measure the volume of gas using a gas syringe or a measuring cylinder

Question 13

What is the water absorbed by plant roots used for

Answer 13

• Carrying dissolved mineral ions
• Keeping cells rigid
• Cooling the leaves
• Photosynthesis

Question 14

What are root hair cells used for

Answer 14

They provide an extended surface area so that water and mineral ions can be absorbed, they also have thin cell walls so water can flow into the cells quickly

Question 15

Describe how water can enter the root hair cells

Answer 15

Water enters through osmosis into the cytoplasm of the root hair cells
Water can also enter by diffusion and the water diffuses through the cell wall

Question 16

How does active transport work in the root hair cell

Answer 16

• The concentration of mineral ions is great in the root hair cell than the soil
• Minerals cannot diffuse against this gradient
• Proteins in the membrane pump ions into the cell

Question 17

What is transpiration

Answer 17

The flow of water into a root, up the steam and out the leaves

Question 18

What are xylem vessels

Answer 18

Long thick tube in plants that carry water

Question 19

How does transpiration work

Answer 19

• Unbroken chain of water held by weak intermolecular forces of attraction between water
• Water is pulled up the xylem vessels as it evaporates from the xylem vessel in the leaf

Question 20

Factors that affect transpiration

Answer 20

Wind- moves water molecules away from the stomata
Low humidity
Higher temperatures, particles move and diffuse faster
-Greater light intensity, makes the stomata wider

Question 21

How are xylem cells adapted to allow water to flow through them quickly

Answer 21

Thick side walls to provide support, prevent collapsing and will not burst
Dead cells, no cytoplasm to form an empty tube
Tiny pores to allow water an mineral ions to enter the xylem vessels

Question 22

What is translocation

Answer 22

The movement of sugars throughout the plant through phloem cells (in both directions)

Question 23

Name some adaptations of phloem cells

Answer 23

Small amount of cytoplasm for more room

Pores that can pump sucrose solution

Question 24

What do spongy cells do

Answer 24

They do not fit well together, creating spaces that allow gases to diffuse easily

Question 25

How are chloroplasts adapted

Answer 25

Have a lot of chlorophyll and can move away or towards light

Question 26

What are epidermis cells

Answer 26

Form the outer layers of a leaf that are transparent and allow light to pass through easily

Question 27

What does the cuticle do

Answer 27

It’s a waxy cuticle that prevents water loss and stop microorganisms entering the leaf

Question 28

How are cacti adapted

Answer 28

Thick cuticle
Stomata only open at night (carbon dioxide is stored)
Spines instead of leaves (protect stem and minimise surface area)

Question 29

What is tropism

Answer 29

Responding to a stimulus by growing towards or away from it

Question 30

What is phototropism

Answer 30

A tropism caused by light, triggering auxins (plant hormones)

Question 31

How does positive phototropism work

Answer 31

Auxins are produced in the shoots and cause elongation of cells, when light comes from one direction, auxins move to the shaded part of the root, triggering them to elongate to the light

Question 32

What is gravitropism

Answer 32

Growth in the direction of gravity that helps a root reach moisture underground

Question 33

What does gibberellins do

Answer 33

It helps germinate seeds and start to grow shoots and roots

Can be used to make bigger fruit

Question 34

What does ethene gas do

Answer 34

It helps fruit ripen

Question 35

What are selective weedkillers and what do they do

Answer 35

They contain auxins that kill plants with broads leaves but not narrow leaves
Farmers can use these to kill weeds without affecting a crop

Question 36

What is photoperiodism

Answer 36

The response an organism has after a specific number of daylight hours

Question 37

What is germination

Answer 37

The process in which a seed turns into a new young plant