These seven original questions follow the four lessons in the chapter. Write your answer first, then open the model answer.
Questions
Question 1. State one function of the epidermis of a leaf.
Answer
The epidermis protects the inner tissues and reduces water loss, because it is a covering layer that usually has a waxy cuticle.
Question 2. Name the tissue that carries sucrose from the leaves to the roots, and name one structure found beside its tubes.
Answer
Phloem carries sucrose. The sieve tubes have companion cells beside them.
Question 3. A mature stem has tubes with thick walls, no living contents and a lignin stain. Identify the tissue and give two functions.
Answer
The tissue is xylem. It carries water and minerals from the roots upwards, and its lignified walls also support the stem.
Question 4. State two differences between primary growth and secondary growth.
Answer
- Primary growth increases the length of the plant, but secondary growth increases its width.
- Primary growth is caused by the apical meristem, but secondary growth is caused by the vascular cambium and cork cambium.
Question 5. A palm tree keeps growing taller for years, but its trunk stays about the same width. Explain the observation.
Answer
The palm keeps showing primary growth, because its apical meristem keeps making new cells that lengthen the plant. The trunk stays narrow because palms are monocotyledons, which have little or no secondary growth from a vascular cambium.
Question 6. A root is marked at 2 mm intervals from the tip. After a day, the segment 2 to 4 mm from the tip has grown from 2 mm to 6 mm, and the segment 8 to 10 mm is unchanged. Explain the result.
Answer
The 2 to 4 mm segment grew by 4 mm because the new cells made near the tip are enlarging in the zone of elongation. The 8 to 10 mm segment is unchanged because its cells are mature and no longer lengthen.
Question 7. Two groups of seedlings start at 4.0 cm. After 10 days, Group X has a mean height of 9.5 cm, and Group Y, grown without light, has a mean height of 5.5 cm. Calculate the increase for each group and state a conclusion.
Answer
Group X increased by 9.5 − 4.0 = 5.5 cm. Group Y increased by 5.5 − 4.0 = 1.5 cm.
In this test, seedlings given light grew more than seedlings without light. The fixed variables, such as water and temperature, must be the same for the comparison to be fair.
If you got these wrong
Mixed-up tissues in questions 1 to 3 point to relating plant tissues to function. Questions 4 and 5 use comparing primary and secondary growth.
Question 6 needs interpreting meristem activity. Question 7 comes from reading plant-growth investigation data.
Log each slip in the mistake log and paper-error review, then build a timed set with the timed original practice session builder. For a teacher to go through your answers, see online one-to-one Biology tuition.