Plant Responses and Plant Transport

Question 1

Plant shoots grow towards light. Name this response and describe its purpose.

Answer 1

Positive phototropism (allows plants to obtain more light for photosynthesis)

Question 2

Plant roots grow towards gravity. Name this response and describe its role.

Answer 2

Positive geotropism (allows plant greater anchorage in soil and more access to mineral ions/water in the soil)

Question 3

Plant shoots grow away from gravity. Name this response.

Answer 3

Negative geotropism

Question 4

Describe how germinating seeds left in the dark will grow

Answer 4

They will grow directly upwards in a desperate attempt to seek light. They will be tall and spindly.

Question 5

What hormone allows plant shoots to bend towards the light?

Answer 5

Auxin

Question 6

Describe the role of phloem

Answer 6

Transporting sucrose and amino acids between the leaves and other parts of the plant

Question 7

Describe the role of the xylem

Answer 7

Transport of water and mineral ions from the roots to the other parts of the plant

Question 8

Describe how water is absorbed by root hair cells

Answer 8

Water enters by osmosis from a region of higher water concentration (soil) to a region of lower concentration (cell cytoplasm) across a partially permeable membrane (cell membrane of root hair cell)

Question 9

Describe how mineral ions are absorbed by root hair cells

Answer 9

By active transport - against the concentration gradient using ATP from respiration

Question 10

Describe how water is pulled towards the leaves from the roots

Answer 10

The transpiration stream/pull - water enters at roots and leaves via stomata (transpiration - water here is a waste product of aerobic respiration).

Question 11

Define transpiration

Answer 11

The evaporation of water from the surface of a plant

Question 12

State 3 factors that affect the rate of transpiration

Answer 12

Humidity
Wind Speed
Temperature
Light Intensity

Question 13

What apparatus can be used to measure the effects of different environmental conditions on the rate of transpiration?

Answer 13

Potometer

Question 14

Describe how a root hair cell is adapted for absorption

Answer 14

Long finger-like projections to increase the surface area for absorption

Question 15

Suggest why a root hair cell contains no chloroplasts

Answer 15

Underground in the roots (no access to light) so no photosynthesis can take place