Plant Nutrition | 6

Question 1

Photosynthesis

Answer 1

Photosynthesis is a metabolic reaction occurring in plants in which light energy converts raw materials into carbohydrates such as glucose, which can be stored in cells and used as an energy source via respiration.

Photosynthesis occurs in the chloroplasts of plant cells.

Chloroplasts contain chlorophyll that transfers light energy into chemical energy to make carbohydrates

Question 2

Photosynthesis work and chemical equation

Answer 2

carbon dioxide + water → glucose + oxygen

                      light energy 6CO2 + 6H2O -----------------> C6H12O6 + 6O2
                     Cholorophyll

Question 3

How have plants adapted in terms of photosynthesis

Answer 3

Their leaves have adapted by being broad and thin , with a high concentration of chloroplasts in their cells , which lets them absorb more light energy

Question 4

Why is photosynthesis important for the plant

Answer 4

With the glucose it gets from photosynthesis , it can make all the other substances it needs , provided it has a supply of mineral ions

Question 5

When does photosynthesis occur

Answer 5

Only during the day with sunlight

However , respiration occurs during day and night

Question 6

What are limiting factors of the rate of photosynthesis

Answer 6

Light intensity , carbon dioxide concentration and temperature

More c02 , more the rate of photosynthesis

If the temprature is near the optimum temprature for the enzymes , photosynthesis is faster

More light intensity , faster the photosynthesis

(too much light intensity can lead to a higher temp)

Question 7

Explain why limiting factors is important with farmers and how they use it

Answer 7

Knowledge of limiting factors is useful for farmers as they can reduce the limitation on the rate of photosynthesis due to these factors.

This will mean that the plants have more energy to use for growth, thus the yield is higher and growth time is shorter.

Farmers can reduce the effects of these limiting factors by placing plants in a greenhouse.

Greenhouses trap heat, thus the plants are always kept at their optimum temperature.

In addition, artificial lighting can be used so that the plant can photosynthesize during the night as well

Carbon dioxide can be pumped into the greenhouse

Question 8

Chloroplasts

Answer 8

This is where photosynthesis occurs.

Chloroplasts contain chlorophyll which allows light energy to be absorbed and converted to chemical energy.

Question 9

Cuticle

Answer 9

The cuticle is a clear waxy layer that surrounds the leaf.

This provides waterproofing and reduces water loss from the leaf without reducing light absorption

Question 10

Guard Cell and stoma

Answer 10

Stomata are located on the lower side of the leaf and allow carbon dioxide in by diffusion, and water vapour and oxygen out of the leaf by diffusion.

Guard cells surround the stomata and can control the opening and closing of the stomata to limit water loss from the plant.

When there is a limited water supply, the guard cells cause the stomata to close to prevent water loss.

This, however, also reduces the diffusion of carbon dioxide through the stomata for use in photosynthesis, so can cause carbon dioxide to become the limiting factor and reduce the rate of photosynthesis.

Plants in hot places often have fewer stomata to reduce water loss. Some plants, for example cacti, only open their stomata at night.

Question 11

Upper and Lower epidermis

Answer 11

the epidermis acts as a protective barrier around the leaf to prevent pathogens entering and causing harm to the organism.

Epidermis cells are transparent to let light pass through and do not contain chloroplasts

Question 12

Palisade mesophyll

Answer 12

these cells are positioned near the top of the leaf where most sunlight hits, thus palisade cells are adapted to absorb light energy efficiently.

The palisade layer cells contain many chloroplasts to carry out photosynthesis.

There are also gaps between the cells to allow for efficient gas exchange and osmosis to occur.

CO2 and water move into the cells to be used in the photosynthesis reaction.

Question 13

Spongy mesophyll

Answer 13

This is the lower layer of the leaf.

Cells are loosely spaced and have a large surface area to allow rapid diffusion of CO2,
water and oxygen when the stomata are open.

Question 14

Vascular bundles

Answer 14

vascular bundles form the plant’s transport system.

They consist of the xylem and the phloem, as well as other cells around them which provide support.

Question 15

Xylem

Answer 15

the xylem is used to transport water through plants from the roots in transpiration.

The xylem is made from hollowed-out dead cells that have the ends removed to make a tube for water to pass through.

They have a thick cell wall to provide structural strength and are thin to allow capillary action.

Question 16

Phloem

Answer 16

the phloem is made of living cells and is used to transport sugars and food nutrients in translocation.

The cells of the phloem are adapted by having no nucleus. (Can carry more nutrients)

Question 17

Nitrate ions in plants

Answer 17

Minerals are taken up actively by root hair cells

nitrate ions are used in the plant to build amino acids, and thus proteins and enzymes. Without nitrate ions, the plant would not be able to grow or repair itself.

(poor growth) (will lead to death)

Question 18

Magnesium ions in plants

Answer 18

magnesium ions are used to make chlorophyll.

thus, a lack of magnesium ions will lead to a lack of chlorophyll, meaning that photosynthesis cannot occur.

This means that sugars cannot be formed through photosynthesis, therefore the plant will not have a sufficient enough energy source to grow and repair itself.

(yellow leaves)