Plant Responses and Plant Transport Flashcards
Plant shoots grow towards light. Name this response and describe its purpose.
Positive phototropism (allows plants to obtain more light for photosynthesis)
Plant roots grow towards gravity. Name this response and describe its role.
Positive geotropism (allows plant greater anchorage in soil and more access to mineral ions/water in the soil)
Plant shoots grow away from gravity. Name this response.
Negative geotropism
Describe how germinating seeds left in the dark will grow
They will grow directly upwards in a desperate attempt to seek light. They will be tall and spindly.
What hormone allows plant shoots to bend towards the light?
Auxin
Describe the role of phloem
Transporting sucrose and amino acids between the leaves and other parts of the plant
Describe the role of the xylem
Transport of water and mineral ions from the roots to the other parts of the plant
Describe how water is absorbed by root hair cells
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)
Describe how mineral ions are absorbed by root hair cells
By active transport - against the concentration gradient using ATP from respiration
Describe how water is pulled towards the leaves from the roots
The transpiration stream/pull - water enters at roots and leaves via stomata (transpiration - water here is a waste product of aerobic respiration).
Define transpiration
The evaporation of water from the surface of a plant
State 3 factors that affect the rate of transpiration
Humidity
Wind Speed
Temperature
Light Intensity
What apparatus can be used to measure the effects of different environmental conditions on the rate of transpiration?
Potometer
Describe how a root hair cell is adapted for absorption
Long finger-like projections to increase the surface area for absorption
Suggest why a root hair cell contains no chloroplasts
Underground in the roots (no access to light) so no photosynthesis can take place