Test 23/9/21

Question 1

cornea

Answer 1

A curved transparent disc at the front of the eye. Does most of the focussing.

Question 2

pupil

Answer 2

A circular opening whose size is controlled by the Iris.

Question 3

lens

Answer 3

It is soft, flexible and transparent. Its shape can be changed to fine tune the focussing of light onto the retina

Question 4

ciliary muscles

Answer 4

A ring of muscle at the edge of the eye which circles the lens. When it relaxes, the lens gets thinner. When it contracts, the lens gets fatter.

Question 5

suspensory ligament

Answer 5

Strong fibres which attach the lens to the ciliary muscle

Question 6

retina

Answer 6

Contains light sensitive cells called rods and cones

Question 7

optic nerve

Answer 7

Consists of many neurones which carry impulses from the retina to the brain

Question 8

fovea

Answer 8

The region of the retina with the greatest number of cones

Question 9

conjunctivia

Answer 9

A mucous membrane that covers the eye to prevent infection

Question 10

Dim light eyes

Answer 10

Radial muscles contract
Circular muscles relax
Iris narrower
Pupil dilates

Question 11

Bright light eye

Answer 11

Radial muscles relax
Circular muscles contract
Iris wider
Pupil constricts

Question 12

Photosynthesis word and symbol equation

Answer 12

Carbon dioxide + water —> glucose + oxygen

6CO2 + 6H2O —> C6H12O6 + 6O2

Question 13

How does carbon dioxide affect the rate of photosynthesis?

Answer 13

More carbon dioxide = faster reaction

As there are more molecules to collide with enzymes

However, it will reach a point when adding more carbon dioxide has no effect, there is a lack of energy

Question 14

How does light intensity affect the rate of photosynthesis?

Answer 14

Brighter light = increased rate of photosynthesis

As there is more energy for the reaction to occur

This doesn’t last forever, as at high light intensities, a different factor is limiting and the graph levels off

Question 15

How does temperature increase the rate of photosynthesis?

Answer 15

Increasing temperature = faster reaction

Enzymes and substrates have more kinetic energy and collide more often

However, at too high temperatures, photosynthesis decreases and the reaction stops

This is because the enzymes carrying out this stage of the photosynthesis have been denatured

Question 16

MAGNESIUM (Mg)

Use by plant

Symptoms of deficiency

Answer 16

To make chlorophyll

Yellow leaves

Question 17

NITRATES (NO3-)

Use by plant

Symptoms of deficiency

Answer 17

Amino acids (therefore proteins)
Nucleic acids (DNA and RNA)

Stunted growth

Question 18

PHOSPHATES (PO43-)

Use by plant

Symptoms of deficiency

Answer 18

Nucleic acids (RNA and DNA)

Poor root growth
Purple younger leaves

Question 19

What happens to the eye when focusing on a far away object?

Answer 19

Relaxing ciliary muscles
Meaning suspensory ligaments are pulled tight
Lens is pulled thin and has a less convex shape

Therefore less refraction of light

Question 20

What happens to the eye when focussing on an object close up?

Answer 20

Contracting the ciliary muscles
Meaning suspenseful ligaments are therefore slack
Lens is not stretched out so becomes thicker with more convex shape

Therefore more refraction of light

Question 21

How is the leaf specially adapted for photosynthesis?

Surface area and thickness

Answer 21

The leaf has a large surface area and is thin, to maximise absorption of sunlight by the photosynthetic sells, it also increases the number of stomata, so thatthe carbon dioxide can diffuse quicker

Question 22

How is the leaf specially adapted for photosynthesis?

Upper epidermis

Answer 22

The upper epidermis is transparent allowing light to penetrate to the mesophyll

Question 23

How is the leaf specially adapted for photosynthesis?

Palisade cells

Answer 23

The palisade cells are long, thin and tightly packed
they contain large numbers of chloroplasts
this maximises the absorption of sunlight energy
the palisade mesophyll is the main site of the photosynthesis

Question 24

How is the leaf specially adapted for photosynthesis?

Stomata

Answer 24

The stomata allows gases to diffuse into the air spaces of the leaf
this provides a short diffusion distance for carbon dioxide

Question 25

How is the leaf specially adapted for photosynthesis?

Xylem

Answer 25

The xylem transports water into the leaves

this then provides a short diffusion distance for water to diffuse into the photosynthesis cells

Question 26

How is the leaf specially adapted for photosynthesis?

Phloem

Answer 26

The phloem vessels transport sugars made in photosynthesis to other parts of the plant