Topic 6-Plant structures and their functions

Question 1

What is photosynthesis?

Answer 1

Plants and algae (type of protist) trap energy transferred by light from the sun and transfer it to molecules of a sugar called glucose. When animals eat plants they get this energy.

Question 2

What are the materials in an organism?

Answer 2

It’s biomass.

Question 3

What is the word equation for photosynthesis?

Answer 3

Carbon dioxide + water -> glucose + oxygen

Question 4

Where does photosynthesis occur?

Answer 4

Chloroplasts which contain a green substance called chlorophyll thst traps light energy.

Question 5

Is photosynthesis exothermic or endothermic?

Answer 5

Products have more energy than reactants so it is endothermic.

Question 6

What happens when glucose molecules are made?

Answer 6

They are linked together to form a polymer called strarch which stays in the chloroplasts until the reaction stops. The starch is then broken down into simpler substances which are moved to the cytoplasm to make sucrose.

Question 7

What are palisade cells?

Answer 7

Palisade cells are near the top of the leaf which are packed with chloroplasts. More sunlight can be absorbed.

Question 8

What are stomata?

Answer 8

Tiny pores which allow carbon dioxide to diffuse into the leaf. The stomata are opened and closed by guard cells.

Question 9

When do the stomata open and close?

Answer 9

In light, water flows into pairs of guard cells making them rigid which opens the stomata. At night, water flows out of the guard cells which makes them lose rigidness causing the ctomata to shut.

Question 10

Why are leaves thin?

Answer 10

So carbon dioxide can diffuse in easily and oxygen can escape eaily (gas exchange).

Question 11

Why do plants grow slower on mountains?

Answer 11

Colder and less concentration of air (thinner air).

Question 12

What is a limiting factor?

Answer 12

A factor that prevents a rate increasing:

C02 concentration, temperature and light intensity.

Question 13

How do you calculate light intensity?

Answer 13

inverse square law (inversely proportional)

Question 14

Explain the core practical on light intensity and photosynthesis.

Answer 14

Question 15

What is water absorbed by roots used for?

Answer 15

Carrying dissolived mineral ions

keeping cells rigid

cooling the leaves when it evaporates

photosynthesis

Question 16

How are root hair cells specialised?

Answer 16

Large surface area to absorb water and mineral ions quicker. They also have thin cell walls so that the flow of the water into cells is not slowed down.

Question 17

Explain diffusion in cell roots.

Answer 17

Cell walls have an open structure allowing water particles to diffuse towards the middle of the root (more to less so down concentration gradient).

Question 18

Explain osmosis in root hair cells.

Answer 18

Question 19

Explain active transport in root hair cells.

Answer 19

Question 20

What is transpiration?

Answer 20

Flow of water into a root, up the stem and out the leaves.

Question 21

What are xylem vessels?

Answer 21

They form tiny continious pipes leading from a plants roots tip into its leaves. Inside the vessels is an unbroken chain of water.

Question 22

What other factors increase transpiration?

Answer 22

higher temp-particles move and diffuse faster

greater light intensity makes the stomata wider

Question 23

Structure and adaptions of xylem.

Answer 23

Question 24

Phloem structure and further explanation.

Answer 24

Plants make sucrose from the glucose and strarch made by photosynthesis. Sucrose is translocated in the sieve tubes of the phloem tissue. The large central channel in each sieve cell is conncected to its neighbours by holes, through which sucrose solution flows. Companion cells actively pump sucrose into or out of the sieve tubes.

Question 25

What are the spongy cells?

Answer 25

They are irregularly shaped and do not fit together to make air spaces, this allows gases to diffuse easily inside a leaf.

Question 26

What is a epidermis cell?

Answer 26

They form the outer layers of a leaf, holding the leaf together and protecting the cells inside. They are transparent so light can pass through them easily. They also produce a waterproof waxy cuticle to help prevent water loss, this also stops microorganisms entering.

Question 27

Why do some plants have needle shaped leaves?

Answer 27

Needles maintain water and seeds. They also have less wind resistance so they are less likely to fall over in a storm.

Question 28

How can plants reduce water loss?

Answer 28

They trap water vapour close to their leaves which slows rate of difufusion. Plants use tiny hairs to trap water vapour.

Question 29

What is a stimulus?

Answer 29

A change in environment.

Question 30

What is a tropism?

Answer 30

Responding to a stimulus by growing towards or away from it.

Question 31

What is phototropism?

Answer 31

Tropism caused by light.

Question 32

How do plants respond to stimuli and what is positive phototrism caused by?

Answer 32

By plant hormones. positive phototropism is caused by hormones called auxins

Question 33

Where are auxins produced and what do they cause?

Answer 33

Tips of a shoot where they cayse elongation of the cells. If a shoot is grown with light coming from only one direction auxins will move to the shaded side so the shaded side can elongate more

Question 34

What do the auxins found in root tips do?

Answer 34

They cause cells to stop elongating and this causes positive gravitropism-growth towards direction of gravity which helps root to anchor the plant in place and to reach moisture underground.

Question 35

what do gibberellins do?

Answer 35

They help seeds to germinate and start to grow roots and shoots (hormone).

Question 36

What does ethene do?

Answer 36

It is a gas that helps fruit to ripen (hormone).

Question 37

how are auxins used by plant growers?

Answer 37

Artificial auxins can cause plants to grow uncontrollably which can kill them. Selective weedkillers contain artificial auxins to kill plants with long leaves which block sunlight.

Question 38

What are rooting powders?

Answer 38

They contain auxins which cause roots to develop quicker.

Question 39

What are the uses of gibberelins

Answer 39

They can be sprayed on some plants to make them grow bigger fruits and they can cause some plants to produce fruits with no seeds.

Question 40

What is photoperiodism?

Answer 40

A response of an organism to the number of daylight hours in a day.

Question 41

What is the chemical equation for photosynthesis?

Answer 41

Question 42

What is a benefit of a plant being day neutral?

Answer 42

Plants can flower all year round and are not limited to one period of the year.

Question 43

How does water move from cell to cell in a leaf?

Answer 43

Osmosis from an area of high concentration to an area of low concentration through a pratially permiable membrane.

Question 44

Why can plants grow easier in open grassland?

Answer 44

more water

more sunlight

warmer

Question 45

How do changes to the guard cell help the plant to survive?

Answer 45

Guard cells change shape to reduce water loss as there is less transpiration.

Question 46

Why is waxy cuticle important?

Answer 46

Surrounds the leaf and prevents water loss/dehydration.

Question 47

How does the water get pulled up the xylem vessel?

Answer 47

Due to to the weak forces of atraction between the water molecules. Water is pulled up the xylem vessels in the stem as water evaporates from the xylem vessels in the leaves. As the water vapour diffuses out out of a leaf, more water evaporates from the xylem inside the leaf.

Question 48

How do conifers reduce water loss?

Answer 48

Conifers do this by having stomata located in small pits where water vapour collects as it has less exposure to air movement.

Question 49

What is a nexample of a cell that produces a waxy cuticle and how does it help?

Answer 49

Epidermis cell produce a waterproof waxy cuticle to help prevent water loss, this also stops microorganisms entering.