Answers · Kingdoms and animal groups

Kingdoms and animal groups — return questions key

Check meaning, not exact wording. These are teaching points, not official Cambridge marks.

1. VR1 · Return

Model answer. a. Plants are made of many cells with cellulose cell walls and chloroplasts, and they make their own food by photosynthesis. Option b describes the animal kingdom. Staying in one place (c) and having roots (d) do not decide a kingdom: a sea anemone stays in one place, and pondweed floats.

A full answer includes

a: many cells with cell walls and chloroplasts, making its own food by photosynthesis.

Also accept

Watch for

“Anything that stays in one place is a plant.” — Many animals stay fixed to one spot, like the sea anemone. Look for cell walls, chloroplasts and photosynthesis.

2. VR2 · Return

Model answer. Birds have feathers, a beak and wings, and they lay eggs with hard shells. Reptiles have dry skin covered in scales. Amphibians have moist skin with no scales, and they lay soft eggs in water. Fish have scales and fins, and they breathe with gills.

A full answer includes

g1: feathers.
g2: hard.
g3: scales.
g4: moist.
g5: water.
g6: gills.

Also accept

feathers; hard; scales; moist; water; gills

Watch for

“Amphibians have scales like reptiles.” — Amphibian skin is moist with no scales; dry skin with scales is a reptile feature.
“Bird eggs have soft shells.” — Bird eggs have hard shells; soft eggs laid in water are an amphibian feature.

3. VR3 · Return

Model answer. c. Only mammals have mammary glands and feed their young on milk. Birds, reptiles and most adult amphibians breathe air with lungs too (a), every vertebrate has a backbone (b), and reptiles and amphibians have four legs as well (d).

A full answer includes

c: mammary glands that make milk for the young are found only in mammals.

Also accept

Watch for

“Breathing air makes an animal a mammal.” — Birds, reptiles and adult amphibians breathe air too; only mammals feed their young on milk.

4. JR1 · Return

Model answer. a. Insects have three body parts (head, thorax and abdomen), three pairs of legs and one pair of antennae. Option b describes arachnids and option c crustaceans. Many insects have wings, but not all, and size and habitat do not decide the group (d).

A full answer includes

a: three body parts, three pairs of legs and one pair of antennae.

Also accept

Watch for

“Every insect has wings.” — Many insects have wings, but a worker ant has none; three body parts, three pairs of legs and one pair of antennae decide the group.

5. JR2 · Return

Model answer. An arachnid has two body parts and four pairs of legs. An arachnid has no antennae. A crustacean has two pairs of antennae. A myriapod has a long body of many segments with legs on each.

A full answer includes

g1: two.
g2: four.
g3: no.
g4: two.
g5: segments.

Also accept

two; four; no; two; segments

Watch for

“Arachnids have one pair of antennae.” — Arachnids have no antennae at all.
“Crustaceans have one pair of antennae, like insects.” — Crustaceans have two pairs of antennae; on a woodlouse one pair is tiny.

6. JR3 · Return

Model answer. a, c and e. The crab, the centipede and the worker ant each have jointed legs, an exoskeleton and a segmented body. The lizard (b) and the frog (f) have jointed legs too, but their skeleton is bone inside the body and they have a backbone: they are vertebrates. The sea anemone (d) has no legs and no exoskeleton.

A full answer includes

a, c and e: the crab, the centipede and the worker ant have jointed legs, an exoskeleton and a segmented body.

Also accept

a, c, e

Watch for

“Any animal with legs that bend is an arthropod.” — A lizard and a frog have jointed legs too, but they have a backbone and a skeleton inside the body, not an exoskeleton.
“A centipede is a worm, not an arthropod.” — A centipede has jointed legs, an exoskeleton and a segmented body: it is an arthropod (a myriapod).

7. XR1 · Return

Model answer. b. A single cell with no nucleus, a loop of DNA in its cytoplasm and a cell wall is a prokaryote. Protoctists (a), fungi (c) and plants (d) all have a nucleus.

A full answer includes

b: a single cell with no nucleus and a loop of DNA is a prokaryote.

Also accept

Watch for

“Every single cell is a protoctist.” — Protoctists have a nucleus; a single cell without one is a prokaryote.

8. XR2 · Return

Model answer. A virus is genetic material inside a protein coat. A monocotyledon has one cotyledon in each seed and leaves with parallel veins. A fern reproduces by spores, not seeds. A dicotyledon has two cotyledons in each seed.

A full answer includes

g1: protein.
g2: one.
g3: parallel.
g4: spores.
g5: two.

Also accept

protein; one; parallel; spores; two

Watch for

“A virus has a cell wall around it.” — A virus has a protein coat around its genetic material; it is not a cell.
“Monocots have a branching network of veins.” — Monocots have parallel veins; dicots have a branching network.

9. XR3 · Return

Model answer. A fungus has no chloroplasts, so it cannot make its own food by photosynthesis. Its hyphae release enzymes onto dead or living matter, such as dead leaves, digest it outside the body and absorb the dissolved food.

A full answer includes

It has no chloroplasts, so it cannot make its own food.
Its hyphae release enzymes onto dead (or living) matter, digest it outside the body and absorb the dissolved food.

Also accept

no chloroplasts; hyphae release enzymes, digest food outside the body, absorb the dissolved food

Watch for

“A mushroom makes its food by photosynthesis, like a plant.” — A mushroom has no chloroplasts; it digests dead material outside its body.

10. XR4 · Return

Model answer. a. A single cell with a nucleus and no cell wall, which swims and takes in food, is a protoctist, like Paramecium. (Some protoctists, such as Chlorella, do have a cell wall; here the swimming and taking in food also point to a protoctist.) A single cell with no nucleus (b) is a prokaryote. A single cell with a nucleus and a wall not made of cellulose, with no chloroplasts (c), is a fungus such as yeast. Many cells with cellulose walls and chloroplasts (d) make a plant.

A full answer includes

a: a single cell with a nucleus and no cell wall is a protoctist.

Also accept

Watch for

“Every single cell with a nucleus is a protoctist.” — Yeast is one cell with a nucleus too, but it has a cell wall not made of cellulose and no chloroplasts: it is a fungus.