Topic 1- Plants

Question 1

Recall the method of the investigation of water loss in plants

Answer 1

1) tie a polythene bag around the stem and pot of a plant. (Prevents water from evaporating from the soil in the pot)
2) place it inside a bell jar that stands on a vasalined glass plate. (Prevents exchange of gases with the outside of the jar)
3) leave in partly exposed, sunny site
4) observe the bell jar after 24 hours

Question 2

What is the result and conclusion of the investigation of water loss in plants?

Answer 2

Result- droplets of water have formed on the inside of the bell jar.

Conclusion- the water from the inside of the jar must’ve come from the plant because there no water can pass into the jar or evaporate from the soil.

Question 3

Recall the method of the investigation of the rate of transpiration from a plant cutting

Answer 3

1) cut a shoot from a plant and place it in a measuring cylinder
2) pour a thin layer of oil over the water.(prevents evaporation of water directly from the surface of the water)
3) weigh the whole apparatus
4) record results in a table
5) leave for a set period of time
6) weight the apparatus again
7) calculate the change in mass

Question 4

What is the result and conclusion of the investigation of the rate of transpiration from a plant cutting?

Answer 4

Result- the mass of the apparatus will have decreased.

Conclusion- water has been lost from the measuring cylinder. Water couldn’t evaporate directly from the surface of the water. It must have travelled up the stem of the plant and evaporated from the leaves. (Transpiration)

Question 5

What are the factors that affect the result of the investigation of the rate of transpiration from a plant cutting?

Answer 5

Humidity
Movement of air
Healthy cuttings will lose water steadily
Unhealthy cuttings may not work as well

Question 6

Recall the method of the investigation of stomata. (Epidermal impression of a leaf)

Answer 6

1) the upper surface of the leaf is painted with a thin layer of clear nail varnish.
2) leave for 10-15 minutes to allow the varnish to dry
3) remove the layer of varnish by attaching clear sticky tape to it, peeling it from the leaf surface and sticking it to a microscope slide.
4) observe the slide with. Microscope and count the number of stomata in the field of view.
5) repeat for lower part of leaf and compare results

Question 7

What is the result and conclusion of investigating stomata?

Answer 7

Result- the lower surface contains the highest number of stomata.

Conclusion- the function of the stomata is to allow gas exchange between the cells of the leaf and the air. However, water is also lost by diffusion through open stomata. Having most of the stomata on the lower surface of the leaf shades them from the heat of the sun, and is an adaptation to reduce water loss.

Question 8

Name five pieces of equipment needed for the investigation of water loss in plants and state what you may experiance

Answer 8

Bell jar
Glass plate
Vaseline 
Plant
Polythene bag
Experience water droplets at the top of the bell jar

Question 9

What is a stomata?

Answer 9

Pores in the surface of the leaf that allow water to pass out.
They allow gaseous exchange to occur.

Question 10

What is a stoma?

Answer 10

A gap in the guard cell that allows water to pass out

Question 11

Recall the method of the investigation of comparing water loss from leaves

Answer 11

1) four leaves are removed from a green plant and their stem’s are covered in vaseline. (Prevents water loss from the cut ends)
2) leaf 1- vaseline on upper surface of leaf
Leaf 2- vaseline on lower surface of leaf
Leaf 3- vaseline on upper and lower surface of leaf
Leaf 4- no vaseline

Question 12

State the appearance and explanation of the leaf that has vaseline covering the upper surface of the leaf during the investigation of water loss from leaves

Answer 12

Appearance- slightly wrinkled
Explanation- there are less stomata on the upper surface of a leaf. The vaseline has only prevented a small amount of water loss.

Question 13

State the appearance and explanation of the leaf that has vaseline covering the lower surface of the leaf during the investigation of water loss from leaves

Answer 13

Appearance- almost fresh

Explanation- stomata found on the lower surface of the leaf. The vaseline has prevented most of the water loss.

Question 14

State the appearance and explanation of the leaf that has vaseline covering the upper and lower surface of the leaf during the investigation of water loss from leaves

Answer 14

Appearance- fresh

Explanation- the vaseline prevented water loss through both surfaces of the leaf

Question 15

State the appearance and explanation of the leaf that has no vaseline during the investigation of water loss from leaves

Answer 15

Appearance- wrinkled and dried out

Explanation- water had been lost through stomata of both surfaces

Question 16

What are the three environmental factors affecting transpiration?

Answer 16

Temperature
Humidity
Wind speed

Question 17

How does the temperature affect transpiration?

Answer 17

Temperature increases, water molecules have more kinetic energy. Therefore, move faster , causing an increase in transpiration.

Question 18

How does humidity affect the rate of transpiration?

Answer 18

An increase of humidity means the lower the concentration gradient of water between air and the intercellular spaces in the spongy layers of a leaf. A decrease of diffusion of water out of stomata

Question 19

How does wind speed affect the rate of transpiration?

Answer 19

An increase of wind speed carries away more water vapour from near the leaf’s surface and increases the rate of diffusion of water vapour out of the stomata

Question 20

Recall the method of the investigation of using a simple potometer to measure transpiration rate

Answer 20

1) set bubble to 0 by using the tap to release water from the water reservoir.
2) measure the time taking for the bubble to move a set distance.
OR
measure how far the bubble moves in a set period of time.
3) record results
4) repeat experiment

Question 21

What happens during the investigation of using a simple potometer to measure transpiration rate?

Answer 21

An air bubble is introduced into the capillary tube at the start.
As water evaporates through the stomata of the leaves, water is drawn up the capillary tube causing the bubble to move

Question 22

What does the wax cuticle allow the plant to do?

Answer 22

Reduce water loss

Question 23

What doe the pallisade layer contain?

Answer 23

Chloroplasts for photosynthesis

Question 24

In the structure of a leaf, what does the air space allow the leaf to do?

Answer 24

Allow gaseous exchange

Question 25

What do the xylem transport?

Answer 25

Water

Question 26

What do the phloem transport?

Answer 26

Sugar

Question 27

What do the spongy layer contain?

Answer 27

Large air spaces to allow gaseous exchange

Question 28

What is the transpiration stream?

Answer 28

The constant flow of water through a plant

Question 29

Describe the 7 steps of the transpiration stream

Answer 29

1) water enters the plants through root hair cells by osmosis.
2) water moves from cell to cell in the root by osmosis.
3) water moves into the xylem by osmosis.
4) water molecules stick together and this causes water to be pulled up the xylem as a column.
5) water moves from cell to cell by osmosis.
6) water evaporates from some of the leaf cells, causing more water to be pulled up the xylem.
7) water diffuses from the air spaces in the spongy layer out of the stomata into the air

Question 30

How does water enter the plant?

Answer 30

Water enters the plant from an area of high water concentration to an area of low concentration in the root hair cell, through a partially permeable membrane.(osmosis)

Question 31

What allows the root cell to take in more water faster?

Answer 31

The increased surface area

Question 32

How are minerals up taken by the plant when the plant has a higher concentration?

Answer 32

Active transport

Question 33

What are factors that affect active transport?

Answer 33

>needs energy
>energy is released during respiration
Any factor that effects respiration affects active transport:
> glucose concentration
> oxygen
> temperature
> toxic substances

Question 34

What do phloem vessels transport?

Answer 34

Transport sugar and other substances that are produced by cells to all other parts of the plant

Question 35

What do xylem vessels transport?

Answer 35

Transports water and mineral ions from roots to the rest of the plant

Question 36

What are groups of phloem and xylem vessels called?

Answer 36

Vascular bundles

Question 37

What are the phloem’s functions?

Answer 37

Carries sugar from the photosynthetic areas to other parts of the plant.
Sugar is moved to other parts of the plant for use in respiration and converted into starch for storage.

Question 38

What are the xylem’s functions?

Answer 38

Transport water from the roots to the rest of the plant
Transport minerals such as KPN around the plant dissolved in water.
Support the plant. Xylem vessels in the shoots and roots of mature plants are inflexible and strong to give support to the plant.

Question 39

Recall the method for the investigation of a dye through a flowering plant

Answer 39

1) take a white flower with a long stalk e.g. A chrysanthemum and cut the stalk carefully lengthwise.
2) put each half of the stalk into a measuring cylinder containing either plain water or water to which food dye has been added.
3) tape the measuring cylinders to the plastic tray so that they don’t fall over.
4) leave the flower for a few hours
5) observe where the dye ends up in the flower head

Question 40

Give an explanation of the results obtained of the investigation into the movement of a dye through a flowering plant

Answer 40

Water and dye are pulled up through xylem vessels. When they reach the petals, the water evaporates from pores in the petal surface but the dye remains in the cells of the petals. The petal became coloured as dye accumulates in them. This procedure could be useful for producing quantities of unusually coloured flowers

Question 41

What is water important for, for plants?

Answer 41

Photosynthesis
Transport of minerals
Support

Question 42

How does water support the structure of a plant?

Answer 42

The pressure of the vacuoles pushing against the cell walls keep the cells turgid

Question 43

What are the minerals needed for healthy plant growth and what are the signs of deficiency?

Answer 43

Nitrogen- poor growth
Phosphate- poor root growth
Potassium- yellow leaves