Plants

Question 1

Where all the epidermal tissues found and what is their function?

Answer 1

They are found at the top and bottom of the leaf. They are covered with a waxy cuticle to prevent from water loss from the lead by evaperation.

Question 2

What is the upper epidermis like and why?

Answer 2

It is thin to allow light to pass through

Question 3

What is the lower epidermis like and why?

Answer 3

Is full of little holes called stomata that allow gases to diffuse in and out. Guard cells open and close the stomata

Question 4

Where is the Palisade mesophyll tissue and what is its function?

Answer 4

It is near the top of the leaf and has lots of chloroplast to absorb light for photosynthesis

Question 5

What is the spongy mesophyll like and why?

Answer 5

It has lots of airspaces to provide space for the gases to diffuse in and out the cell

Question 6

What does the phloem transport?

Answer 6

Sugars and amino acids

Question 7

Give adaptations of phloem cells and why they are like this.

Answer 7

Cells are elongated and joined end to end with sieve plates between them. They have pores to allow cell sap to flow through. They are living cells with few sub cellular structures for substances to pass through. The substances can move in both directions. Companion cells provide the phloem with energy to transport substances

Question 8

What is translocation?

Answer 8

The process of moving food substances in the phloem

Question 9

What are Xylem cells specialised for?

Answer 9

To provide and transport water and dissolved mineral ions up the plant to stems and leaves

Question 10

Give properties of the xylem and their functions

Answer 10

Top and bottom cells have no cell walls so they can join together to form the Xylem vessel. Xylem cells are dead and hollow so they contain no sub cellular structures or cytoplasm. Xylem vessels are strengthened by lignin.

Question 11

Water is drawn up the plant in the what stream ?

Answer 11

Transpiration stream

Question 12

What is transpiration?

Answer 12

The loss of water from a plant surface creating a constant flow of water throughout the plant

Question 13

What are the stages of the transpiration stream?

Answer 13

Water diffuses and evaporates out the leaves into the atmosphere, leaving a shortage of water. Water is drawn up the xylem to the leaves to replace the water. This means more water is drawn up from the soil.

Question 14

What (not how) our root hair cells adapted for?

Answer 14

The uptake of water by osmosis and mineral ions by active transport

Question 15

What do guard cells do?

Answer 15

They control gas exchange and water loss by opening and closing the stomata

Question 16

What happens if there is lots of water in the guard cells?

Answer 16

Guard cells become turgid and open the stomata to allow gases to be exchanged and water to escape

Question 17

What happens if the Guard cells are full of little water?

Answer 17

They become flaccid and the stomata closes so little water has lost

Question 18

What is Guard cells sensitive to?

Answer 18

Light which means they open in the day to allow carbon dioxide for photosynthesis and they close in the dark as they can’t photosynthesise

Question 19

What does temperature do to the rate of transpiration?

Answer 19

The higher the temperature means the more the molecules move. This means the water evaporates more and increases transpiration

Question 20

How does humidity affect the rate of transpiration ?

Answer 20

The lower the humidity means the lower the concentration or water outside the leaf. This means there is a steeper concentration gradient and water will diffuse fast increasing the transpiration.

Question 21

How does air movement affect transpiration rate?

Answer 21

Increased air flow decreases the concentration of water outside the leaf meaning a steeper concentration gradient and more transpiration

Question 22

How does light intensity affect the transpiration rate?

Answer 22

Light makes guard cells become turgid and open the stomata increasing transpiration rate.

Question 23

What does a potometer measure ?

Answer 23

The water intake of a plant shoot

Question 24

Equation for the rate of transpiration

Answer 24

Rate of transpiration = distance moved by bubble divided by time