B6

Question 1

What is photosynthesis?

Answer 1

It is a reaction which happens in plants
which traps the sun’s energy to create
glucose (which is used for
respiration).

Question 2

What is the word equation for
photosynthesis?

Answer 2

carbon dioxide + water → oxygen +
glucose

Question 3

What are the reactants of
photosynthesis?

Answer 3

• carbon dioxide
• water

Question 4

What are the products of
photosynthesis?

Answer 4

• glucose
• oxygen

Question 5

Where does photosynthesis occur
in plants?

Answer 5

In the chloroplasts (in the leaf cells)

Question 6

What kind of reaction is
photosynthesis?

Answer 6

Endothermic (because it takes IN light
energy)

Question 7

In plants, what is excess glucose
stored as?

Answer 7

Glucose is stored as starch.

Question 8

In plants, what is the glucose used
for?

Answer 8

Glucose is used for respiration to
release energy.

Question 9

What are the small holes called
which are found on the bottom of
a leaf?

Answer 9

stomota

Question 10

What is the function of stomata?

Answer 10

Gas exchange (O2 out of leaf, CO2
into

leaf)

Question 11

What do you call the cells on either
side of a stoma which control its
opening and closing?

Answer 11

Guard cells

Question 12

When are stomata usually open and
closed?

Answer 12

Closed - at night
Open - during the day

Question 13

How do stomata open?

Answer 13

• Water moves into the guard cells by

osmosis.
- They become rigid (turgid) and open
the stomata.

Question 14

How do stomata close?

Answer 14

• Water moves out of the guard cells

by osmosis.
- The guard cells become less rigid
and close the stomata.

Question 15

How is a leaf adapted?

Answer 15

• Large surface area to absorb more

light.
- Have chloroplasts near the top of the
leaf for photosynthesis.
- Have a waxy cuticle which reduces
water loss.

Question 16

What three factors affect the rate of
photosynthesis?

Answer 16

• Temperature
• Carbon dioxide concentration
• light intensity

Question 17

What do you call a factor which
prevents the rate of photosynthesis
from increasing?

Answer 17

Limiting factor

Question 18

As light intensity and carbon dioxide
concentration increase, what happens
to the rate of photosynthesis?

Answer 18

• As the factors increase, the rate
  of photosynthesis increases.
• Then the rate of photosynthesis
  will remain the same.

Question 19

As temperature increases, the rate
of photosynthesis increases in the
beginning, why?

Answer 19

As temperature increases, the enzymes
involved in photosynthesis will work
better so the rate will be quicker.

Question 20

Give some uses of water in plants.

Answer 20

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

Question 21

Give an adaptation of the roots.

Answer 21

They have root hair cells to absorb
water.

Question 22

Give 2 adaptations of root hair
cells.

Answer 22

• They have an extension which
  increases their surface area so
  more water can be absorbed.
• They have mitochondria to
  release energy for active
  transport.

Question 23

Give two ways in which water
moves into the root hair cell.

Answer 23

Water moves in by:
- osmosis
- diffusion.

Question 24

How does water move into the
CELL WALL of the root hair cell?

Answer 24

By diffusion.

Question 25

How does water move into the
CYTOPLASM of the root hair cell?

Answer 25

By osmosis (through a partially
permeable membrane).

Question 26

How do minerals, like nitrate ions,
move into a root hair cell?

Answer 26

Minerals move in by active transport.

Question 27

Why do minerals move into a root
hair cell by active transport?

Answer 27

• The minerals must move from
  a higher concentration in the
  soil, to a lower concentration
  in the root hair cells.
• This is against the
  concentration gradient.

Question 28

What are nitrates needed for in
plants?

Answer 28

Nitrates are used to make proteins.

Question 29

What is transpiration?

Answer 29

Transpiration is:

• The movement of water
• Up the plant (one way)
• Through the xylem.

Question 30

What is translocation?

Answer 30

Translocation is:

• The movement of sucrose
• Around (up and down) the plant.
• Through the phloem.

Question 31

In what direction does transpiration
occur?

Answer 31

From the roots to the leaves.

Question 32

How is the xylem adapted?

Answer 32

• Has rings of lignin in the walls to
  prevent it from bursting.
• Cells are dead (have no
  cytoplasm).
• No cell walls between cells.
• Has tiny pores to allow water and
  minerals to enter and leave.

Question 33

How is the phloem adapted?

Answer 33

• Has companion cells which actively
  transport sucrose into the phoem.
• Has holes in the end of cell walls
  to allow liquids to flow.

Question 34

CORE PRACTICAL: In the practical,
why were the algal balls placed in
hydrogen carbonate indicator?

Answer 34

To ensure that carbon dioxide is not a
limiting factor.

Question 35

CORE PRACTICAL: In the practical,
what would be a control experiment
(not control variable)?

Answer 35

Set up another test tube which is
covered in tin foil to prevent light
enetering.

Question 36

CORE PRACTICAL: What are some
control variables for the experiment?

Answer 36

• Volume of indicator
• Number of algae balls
• Temperature

Question 37

CORE PRACTICAL: Why do we place
a large beaker of water between the
light and the test tubes of algae balls?

Answer 37

• This is called a heat sink.
• It absorbs any heat (but lets light
  through) so temperature does not
  affect the rate of the experiment.