Year 7 Science · Unit 1 · Lesson 4
Challenge Worksheet
Learning Goals
1. Plants are split into four groups by asking three yes/no questions in turn. Write the three questions, in the order a botanist would ask them (the third question splits the seed plants).
Evaluate the claim
Someone claims…
“Ferns are basically the same as mosses. They are both old-fashioned plants that don’t make seeds.”
2. Evaluate this claim. Say what is correct, what is wrong, and why the difference between ferns and mosses matters for how tall each can grow.
Find the error
Jae’s wattle
Jae picks a “leaf” from a wattle. Its veins run side by side along its length, like a blade of grass. Jae writes: “Parallel veins, so wattles are monocots.” Jae’s teacher adds three more observations of the same wattle: its seedling had two seed leaves, it has one main root with side roots, and its tiny flowers have their parts in fours or fives.
3. Is Jae right? Use all four observations to decide, and explain what Jae’s mistake shows about classifying a plant from one feature.
Read the data
Survey: creek bank or ridge?
A class surveys two 10 m² plots in a Blue Mountains reserve. One plot is on a shady creek bank; the other is on a dry, sunny ridge above it. They count the plants in each group (each patch of moss counts as one).
| Plant group | Shady creek bank | Dry, sunny ridge |
|---|---|---|
| Mosses | 40 | 0 |
| Ferns (tree ferns, bracken) | 12 | 0 |
| Gymnosperms (Macrozamia cycads) | 3 | 6 |
| Angiosperms (gums, wattles, grasses) | 25 | 38 |
| Total | 80 | 44 |
Source: sample class results.
4. Calculate the percentage of the plants on the ridge that are angiosperms. Give your answer to one decimal place.
Answer %
5. A tree fern can grow 10 m tall, yet no ferns were found on the ridge. Use Table 1 to explain why mosses and ferns were missing from the ridge while cycads and angiosperms were not.
6. Twice as many Macrozamia cycads grew on the ridge as on the creek bank. Give two features of these cycads, other than their seeds, that help them survive in dry forest.
A news website says…
The Wollemi pine was found in 1994: about a hundred wild trees growing in one sheltered, moist canyon in the Blue Mountains. It makes cones and never has flowers. A website claims: “Now that it is protected, the Wollemi pine will spread by itself across the dry ridges of the Blue Mountains.”
7. Evaluate the website’s claim. Name the Wollemi pine’s plant group with evidence, and use what you know about how that group is pollinated and how its seeds travel.
Question 1
1. Vascular tissue? (no: moss) (1). 2. Makes seeds? (no: fern) (1). 3. Seeds inside a fruit? (yes: angiosperm; no, cones: gymnosperm) (1). [3 marks]
Evaluate the claim
2. Correct: both reproduce by spores, not seeds (1). Wrong: ferns have vascular tissue; mosses do not (1). So ferns can carry water up and grow tall (tree ferns to 10 m) (1), while mosses must stay a few centimetres tall (1). [4 marks]
Find the error
3. Jae is wrong: the wattle is a dicot (1). Two seed leaves, a taproot and flower parts in fours or fives all point to dicot; only the veins disagree (1). One feature can mislead, so classify from several features that agree (1). (Many wattles have phyllodes, flat leaf stalks with parallel veins.) [3 marks]
Read the data
4. 38 ÷ 44 × 100 (1) = 86.4% (1). [2 marks]
5. Mosses and ferns reproduce by spores, which need a film of water, so they cannot survive on the dry ridge (1). Vascular tissue lets a tree fern grow tall but not escape that need (1). Cycads and angiosperms make seeds with a food store and tough coat that can wait in dry ground (1). [3 marks]
6. Thick, waxy leaves (1); an underground stem (1). [2 marks]
Question 7
Marking guide: 1 gymnosperm: seeds in cones, no flowers; 1 helps: seeds carry food in a tough coat and need no damp place to germinate; 1 holds back: wind pollination works best where many of its own kind grow close together, and there are only about a hundred trees; 1 holds back: no fruit to attract animals that would carry seeds to new places, unlike a flowering plant; 1 it grows only in a sheltered, moist canyon, which a dry ridge is not; 1 clear judgement (the claim is unlikely). [6 marks]
Model answer: It is a gymnosperm: seeds in cones, no flowers. Its seeds help, because they carry food in a tough coat. But it relies on wind pollination, which works best where many trees grow close together, and there are only about a hundred. It has no fruit, so birds do not carry its seeds away as they do for a lilly pilly. It grows only in a sheltered, moist canyon. So the claim is unlikely.
Common error: thinking a tall tree fern no longer needs water to reproduce.