1. Where is meristem tissue found in plants and what is its function ?
Answer
Meristem tissue is found at the growing tips of roots and shoots. It contains stem cells that divide (by mitosis) to produce new cells for growth (of the root and shoot).
2. Describe what the transpiration stream is.
Answer
The movement of water from roots to leaves in the xylem: water enters root hair cells by osmosis then travels from cell to cell through the root. Water enters the xylem and travels up the stem to the leaves.
3. Give the function of stomata and state where most stomata are found.
Answer
Allow oxygen and carbon dioxide to diffuse into and out of the leaf. They are mainly found on lower surface of a leaf.
4. Describe what "translocation" is.
Answer
The movement of food molecules (dissolved sugars) made in the leaves to the rest of the plant through phloem tissue.
5. The figure below shows a cross-section through a leaf. Name the parts labelled A–G.
Answer
6. Describe how xylem and phloem are adapted for their functions.
Answer
Xylem transports water and mineral ions from the roots. It consists of hollow tubes strengthened by lignin, allowing water to move in continuous columns.
Phloem transports dissolved sugars from the leaves. It consists of elongated cells arranged in tubes, with porous end walls that allow sap to flow easily from one cell to the next.
7. Give some uses of water absorbed by plants.
Answer
Needed for photosynthesis, transports substances in solution or turgidity of cells.
8. Describe the process of transpiration that occurs in leaves.
Answer
Water evaporates from the leaves through the stomata, creating a transpiration pull that draws water upward through the xylem from the roots to the leaves.
9. The figure below shows stomata on the lower epidermis of a leaf. Name the parts labelled X and Y.
Answer
10. The figure below shows the appearance of open and closed stomata. Stomata tend to open under high light intensity, during which potassium ions (K+) move into the guard cells. Explain how the accumulation of K+ in guard cells contributes to the opening of the stomata.
Answer
A high concentration of potassium ions inside guard cells causes water to enter by osmosis. As the guard cells swell and become turgid, the stomata open because the thinner outer wall stretches more than the thicker inner wall.
11. Suggest a method that could be used to estimate the area of a leaf.
Answer
Put the leaf on a piece of cm squared paper and draw round the leaf. Count the number of squares inside the leaf outline.