IGCSE Biology | Practice Test | 25 Questions
Define transpiration.
State two structural features of a root hair cell that make it well adapted for absorbing water from the soil.
Name the process by which water enters a root hair cell from the soil.
State two functions of xylem in a flowering plant.
Name the tissue in plants that transports sucrose and amino acids.
State three structural features of xylem vessels.
List, in order, the tissues that water passes through on its journey from the soil to a leaf mesophyll cell.
Define translocation.
State two environmental factors that increase the rate of transpiration.
Name the two types of substance transported in the phloem.
A student increases the wind speed around a plant. Explain why this causes the rate of transpiration to increase.
A plant is placed in a very humid atmosphere. Explain why its rate of transpiration will be lower than in dry air.
Explain why a plant wilts if it loses water faster than its roots can absorb it.
A student examines a transverse section of a non-woody dicotyledonous stem under a microscope. Describe where she would find the vascular bundles, and where xylem and phloem are positioned within each bundle.
Explain how two structural features of a root hair cell make it efficient at absorbing water by osmosis.
A student covers all the stomata on a plant’s leaves with petroleum jelly. Explain the effect this would have on:
(a) the rate of transpiration.
(b) the movement of water up the xylem.
Explain how two structural features of xylem vessels make them well suited to transporting water from root to leaf.
A plant is moved from a dim room into bright sunlight. Predict and explain the effect on its rate of transpiration.
Mineral ions are found in higher concentrations inside root cells than in the surrounding soil. Explain how these ions are absorbed into the root hair cells.
A plant is growing in hot, dry, and windy conditions. Give two reasons why this plant is at high risk of wilting.
This question is about the mechanism that moves water up the xylem.
(a) Describe what happens at the leaf surface that creates a pulling force in the xylem.
(b) Explain the role of cohesion in allowing water to be pulled up the xylem.
(c) Explain why xylem vessels must have thick walls for this mechanism to work.
This question is about the position and function of vascular tissues.
(a) Describe the arrangement of vascular bundles in a transverse section of a non-woody dicotyledonous stem. State where xylem and phloem are found within each bundle.
(b) Describe how the arrangement of vascular tissue in a root differs from that in a stem.
(c) State two functions of xylem. For each function, name one structural feature of xylem vessels that makes it suited to that function.
This question is about the movement of water from soil to air.
(a) Using the term water potential, explain why water moves from the soil into a root hair cell.
(b) Describe the complete pathway of water from the soil to the outside air. Name each tissue or structure the water passes through, in order.
(c) Explain how transpiration drives the movement of water up through the xylem.
A student investigates the effect of different conditions on the rate of transpiration. She measures how fast a plant takes up water in each condition.
(a) She finds the plant takes up water faster in moving air than in still air. Explain why wind speed increases the rate of transpiration.
(b) Explain why temperature also affects the rate of transpiration.
(c) Give one limitation of using water uptake to measure the rate of transpiration.
This question compares transport in xylem and phloem.
(a) Describe the role of phloem in translocation. Include: what substances are transported, where they move from, and where they move to.
(b) State two differences between transport in xylem and transport in phloem.
(c) A pest blocks all the phloem in a plant’s stem. Explain two ways this would harm the plant.
