Plants MOCKS

Question 1

The cuticle

Answer 1

The cuticle is located outside the epidermis (made of wax) and protects against water loss

Question 2

The palisade layer

Answer 2

Main site of photosynthesis and has long, narrow, tightly-packed (to capture as much light as possible) cells containing a lot of chloroplasts

Question 3

The spongy layer

Answer 3

Main gas exchange surface of the leaf, absorbing CO2 and releasing oxygen and water vapour
Loosely packed cells with air spaces to allow gases to move in and out

Question 4

The veins

Answer 4

help position the blade so that it is facing the light source

Question 5

The stomata

Answer 5

They provide for the exchange of gases between the outside air and the branched system of interconnecting air canals within the leaf.

Question 6

Roots

Answer 6

They keep plants securely in the ground and are covered with root hair cells which absorb water and nutrients from the soil.

Question 7

Leaf function

Answer 7

produce food for the plant by photosynthesis

Question 8

Stem function

Answer 8

to support the leaves; to conduct water and minerals to the leaves, where they can be converted into usable products by photosynthesis; and to transport these products from the leaves to other parts of the plant, including the roots.

Question 9

role of xylem

Answer 9

transports water and mineral salts from the roots up to other parts of the plant

Question 10

Mature xylem consists of

Answer 10

of elongated dead cells, arranged end to end to form continuous vessels

Question 11

How are leaves adapted for photosynthesis

Answer 11

They are green because they contain lots of chlorophyll to absorb sunlight.
They have a large surface area to maximise the amount of sunlight they can absorb.
They are thin, allowing easy diffusion of gases into and out of the leaf.
They have veins (xylem and phloem) to allow the transport of water, mineral ions and glucose (food).
A waxy waterproof layer which reduces water loss, it is transparent to allow light through the leaf

Question 12

How do root hair cells absorb water

Answer 12

Water is absorbed by the root hair cell by the preocess called, Osmosis. Water passes from a region of high water concentration (wet soil) through a semi-permeable membrane (the cell membrane) to a region of lower water concentration (the cytoplasm)

Question 13

What is transpiration

Answer 13

Transpiration is the evaporation of water from the surface of a plant

Question 14

How is rate of transpiration affected

Answer 14

Temperature
- evaporation and diffusion are faster at higher temperatures

Humidity
- diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air

Wind speed
- moving air removes water vapour, increasing the rate of diffusion of water vapour from the leaf

Light intensity
- the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis

Question 15

Equation for photosynthesis

Answer 15

6CO2 + 6H2O – C6H12O6 + 6O2

Question 16

What does photosynthesis do

Answer 16

converts lights energy to chemical energy

Question 17

How does light intensity affect the rate of photosynthesis

Answer 17

Without enough light, a plant cannot photosynthesise very quickly - even if there is plenty of water and carbon dioxide and a suitable temperature.

Increasing the light intensity increases the rate of photosynthesis, until some other factor – a limiting factor – becomes in short supply.

Question 18

How does temperature affect the rate of photosynthesis

Answer 18

The chemical reactions that combine carbon dioxide and water to produce glucose are controlled by enzymes. As with any other enzyme-controlled reaction, the rate of photosynthesis is affected by temperature.

At low temperatures, the rate of photosynthesis is limited by the number of molecular collisions between enzymes and substrates. At high temperatures, enzymes are denatured.

Question 19

How does CO2 affect the rate of photosynthesis

Answer 19

Carbon dioxide – with water – is one of the reactants in photosynthesis.

If the concentration of carbon dioxide is increased, the rate of photosynthesis will therefore increase.

Again, at some point, a factor may become limiting

Question 20

Geotropic responses of stems and roots

Answer 20

when the stem grows against the force of gravity, this is known as a negative geotropism
when a root grows in the direction of the force of gravity, this is known as a positive geotropism

in a root placed horizontally, the bottom side contains more auxin and grows less - causing the root to grow in the direction of the force of gravity.

The opposite happens in a stem. When a stem placed horizontally, the bottom side contains more auxin and grows more - causing the stem to grow upwards against the force of gravity.

Question 21

Phototropic responses of stems and roots

Answer 21

Phototropism is a response to the stimulus of light.

Responses to stimuli of different parts of the plant
In the plant stem, responses to light are known as a positive phototropism, which means the stem grows towards the light
In the plant root, responses to light are known as a negative phototropism, which means the root grows away from the light

In a stem, the shaded side contains more auxin and grows longer, which causes the stem to grow towards the light. It is vital to note that the plant does NOT bend towards the light.

Auxins have the opposite effect on root cells. In a root, the shaded side contains more auxin and grows less - causing the root to bend away from the light.

Question 22

Insect pollinated plants adaptations

Answer 22

• large and brightly coloured to attract insects
• scented and with nectar to attract insects
• sticky or spiky nectar grains to stick to insects well
• stigma is sticky so pollen grains stick when insect brushes past

Question 23

Wind pollinated plants adaptations

Answer 23

• smooth and light pollen grains - easily carried by the wind without clumping together
• anthers are outside plant and are loose to release pollen easily
• stigma are outside plant and are feathery to make a network to catch drifting pollen grains

Question 24

Growth of pollen tube

Answer 24

When a pollen grain lands on the stigma of a flower of the correct species , a pollen tube begins to grow. It grows through the style until it reaches an ovule inside the ovary. The nucleus of the pollen then passes along the pollen tube and fuses (joins) with the nucleus of the ovule.

Question 25

Conditions needed for seed germination

Answer 25

Water - Lets the seed swell and the embryo start to grow
Oxygen - Needed for aerobic respiration
Warmth - Increases growth rate and enzyme activity (but very high temperatures denature enzymes)