Photosynthesis and plants

Question 1

What is photosynthesis?

Answer 1

A chemical reaction used to make food from light energy, CO2 and H2O.

Plants only and O2 is a waste product from this reaction.

Question 2

What is the word equation for photosynthesis?

Answer 2

Carbon + Water —> Glucose + Oxygen

Question 3

Where does photosynthesis take place?

Answer 3

In the chloroplasts of leaf cells

Question 4

What does chlorophyll do?

Answer 4

Absorb light energy

Question 5

What controls the chemical reactions of photosynthesis?

Answer 5

Enzymes

Question 6

Whats glucose used for?

Answer 6

Respiration

Question 7

What does glucose transform into?

Answer 7

1. Starch for storage
2. Cellulose to make new cell walls
3. Protein for growth
4. Oils for storage

Question 8

How do you test a leaf for starch?

Answer 8

1. Place the leaf in boiling water for a minute - Breakdown all walls
2. Boil the leaf in ethanol (alcohol) - Remove chlorophyll
3. Rinse the leaf in hot water - To soften the leaf to spread on the tile
4. Spread the leaf on a white tile and blot dry - As it allows us to save a colour change better
5. Add a few drops of iodine solution - Added as an indicator test for starch (stored sugar)
6. If leaf turns black, starch is present - chaka chaka

Question 9

Is carbon dioxide needed for photosynthesis?

Answer 9

Yes as it is one of the conditions for it to proceed

Question 10

Which cell layer does most photosynthesis take place?

Answer 10

Palisade layer, has chloroplasts and is near the top

Question 11

What are the three main factors of photosynthesis?

Answer 11

Light Intensity, CO2 concentration, and Temperature.

Question 12

Why does photosynthesis have an optimum temperature?

Answer 12

Photosynthesis is controlled by enzymes which work slowly when too cold and denature when too hot

Question 13

What happens to rate of photosynthesis when you increase light/carbon dioxide concentration?

Answer 13

The rate increases

Question 14

At night what would most likely be the limiting factor for photosynthesis?

Answer 14

Light Intensity

Question 15

Which side of a leaf has stomata?

Answer 15

The underside (the bottom)

Question 16

How does air enter a leaf?

Answer 16

Through the stomata

Question 17

What is the name of the loss of water through stomata?

Answer 17

Transpiration

Question 18

Where does water enter the plant?

Answer 18

Roots, specifically root hairs

Question 19

What is water needed for in plants?

Answer 19

Photosynthesis, carrying minerals, keeping cells turgid (rigid and preventing wilting)

Question 20

What are root hairs?

Answer 20

They increase the surface area that can absorb water or minerals

Question 21

How does water move into the roots?

Answer 21

By osmosis

Question 22

How do minerals enter the roots?

Answer 22

By active transport

Question 23

What do the xylem and phloem transport?

Answer 23

Xylem: Water (one way)
Phloem: Sucrose/sugar (up and down)

Question 24

How is water pulled up the xylem?

Answer 24

After diffusion of water vapour through the stomata, more water is pulled up as a column because the molecules stick together

Question 25

How would wind increase the rate of transpiration?

Answer 25

water molecules blown away, steepening concentration gradient

Question 26

What does the phloem look like?

Answer 26

Living tissue made from columns of interconnecting cells

Question 27

What does the xylem look like?

Answer 27

Tissue made of elongated tubes called xylem vessels

Question 28

What are limiting factors?

Answer 28

The factor that stops the rate of photosynthesis increasing e.g. if there’s too little light, photosynthesis is slow even if CO2 concentration is plentiful therefore, light intensity is the limiting factor.

Question 29

What is transpiration?

Answer 29

The loss of water vapour from a plant by diffusion from the stomata of leaves. Also makes more water being drawn up the plant through the xylem vessels

Loss of water vapour through the leaf

Question 30

What are chloroplasts?

Answer 30

Contains the green pigment, chlorophyll and where photosynthesis takes place

Question 31

What is humidity?

Answer 31

A measure of how much water is in the atmosphere

Question 32

What are mineral salts?

Answer 32

Simple chemicals found in the soil containing elements such as nitrogen, phosphorus and potassium

Question 33

What is the stomata (or a stoma)

Answer 33

Gaps in the epidermis (outer layer) of a leaf that allow gases to diffuse in and out of leaf. It can also open and close

Question 34

What are guard cells?

Answer 34

Cells located around the stomata that open the stomata by pulling apart/coming together if they want to close

Question 35

Why is the waxy cuticle and the upper epidermis transparent?

Answer 35

To allow sunlight to get in

Question 36

How does water enter the plant?

Answer 36

They go through their root hairs. The soil water is more dilute (higher water concentration) therefore osmosis takes place when going inside the root hair cell.

Question 37

What is meant by turgid?

Answer 37

Swollen cells. If the plant has plenty of water its cytoplasm + vacuole have plenty of water

Question 38

Why do plants need a variety of minerals?

Answer 38

For healthy growth

Question 39

What do farmers add to soil if it has mineral deficiencies?

Answer 39

NPK

Nitrogen - nitrates - less chlorophyll, yellow leaves
Phosphorus - phosphates - discoloured purple leaves, poor root growth
Potassium - potassium nitrate - poor growth of flowers and fruit

Question 40

If its a hot day, the stomata closes to reduce transpiration and prevent wilting. What is the disadvantage of it closing?

Answer 40

Gas exchange cannot occur. No CO2 = no photosynthesis :(