Chordate features, subphyla, and vertebrate divisions
Question 1
A learner labels the chordate nerve cord ‘ventral, solid, and double’ while correctly identifying the notochord, gill slits, and post-anal tail. Which correction is accurate?
(a)Change the nerve-cord label to dorsal, solid, and double
(b)Change the nerve-cord label to dorsal, hollow, and single
(c)Change the nerve-cord label to ventral, hollow, and single
(d)Keep the nerve-cord label ventral, solid, and double because that is the chordate pattern
Show answer
(b) Change the nerve-cord label to dorsal, hollow, and single
The label has imported the non-chordate pattern. A chordate nerve cord is dorsal, hollow, and single; the notochord is a separate supportive structure.
Question 2
Which comparison of the central nervous system in chordates and non-chordates matches the chapter?
(a)Chordates—dorsal, solid, double; non-chordates—ventral, hollow, single
The chordate central nervous system is dorsal, hollow, and single. The contrasted non-chordate pattern is ventral, solid, and double.
Fundamental bases of animal classification
Question 3
Profile P has ectoderm and endoderm separated by undifferentiated mesoglea. Profile Q has a body cavity between body wall and gut that is not lined by mesoderm. Which classification is correct?
(a)P is diploblastic; Q is pseudocoelomate.
(b)P is coelomate; Q is acoelomate.
(c)P is diploblastic; Q is coelomate because every body cavity is a true coelom.
(d)P is triploblastic because mesoglea is a third germ layer; Q is pseudocoelomate.
Show answer
(a) P is diploblastic; Q is pseudocoelomate.
P is diploblastic because mesoglea is not a third germ layer. Q is pseudocoelomate because its cavity lacks mesodermal lining; it is not a true coelom.
Question 4
A learner says, 'Every multicellular animal has organ-system organisation, and an incomplete digestive system has no opening.' Which correction is complete?
(a)Every multicellular animal has organ systems, and incomplete digestion means food never enters the body.
(b)Organisation levels vary, but an incomplete digestive system has no opening.
(c)Every multicellular animal has organ systems, but an incomplete digestive system has one shared opening.
(d)Multicellular animals can have lower organisation levels, and an incomplete digestive system has one shared opening.
Show answer
(d) Multicellular animals can have lower organisation levels, and an incomplete digestive system has one shared opening.
Animals differ in organisation level despite all being multicellular; sponges have cellular organisation and cnidarians have tissue organisation. An incomplete digestive system has one opening serving as both mouth and anus.
Porifera, Cnidaria, and Ctenophora
Question 5
Which statement correctly compares the two cnidarian body forms and their roles in metagenesis?
(a)Polyp: sessile and cylindrical, producing medusae asexually; medusa: free-swimming and umbrella-shaped, forming polyps sexually.
(b)Polyp: free-swimming and umbrella-shaped, forming medusae sexually; medusa: sessile and cylindrical, forming polyps asexually.
(c)Both forms are sessile and differ only in the presence of comb plates.
(d)Both forms are sponge stages connected by the canal system.
Show answer
(a) Polyp: sessile and cylindrical, producing medusae asexually; medusa: free-swimming and umbrella-shaped, forming polyps sexually.
The polyp is sessile and cylindrical and produces medusae asexually. The medusa is umbrella-shaped and free-swimming and forms polyps sexually.
Question 6
Which statement correctly links a sponge's level of organisation with its digestion?
(a)Organ-level organisation with separate mouth and anus
(b)Tissue-level organisation with a complete alimentary canal
(c)Cellular-level organisation with intracellular digestion
(d)Organ-system organisation with extracellular digestion in a gut
Show answer
(c) Cellular-level organisation with intracellular digestion
Sponges have loose cellular organisation with division of labour but no true tissues or organs. Digestion occurs inside cells and is therefore intracellular.
Flatworms, roundworms, and segmented worms
Question 7
Which combination correctly identifies the annelid circulatory type and excretory organ?
(a)Closed circulation and nephridia
(b)Open circulation and parapodia
(c)Closed circulation and Malpighian tubules
(d)Open circulation and nephridia
Show answer
(a) Closed circulation and nephridia
Annelids possess a closed circulatory system, so blood remains within vessels. Nephridia perform excretion and osmoregulation.
Question 8
A student says, 'Annelid segmentation is only a pattern of external rings, and their blood directly bathes tissues in an open system.' Which correction is complete?
(a)Segmentation is only external, but circulation is closed.
(b)Segmentation is external and internal with serial repetition, and circulation is closed.
(c)Segmentation is external and internal, but circulation is open.
(d)Segmentation is absent, and circulation is open.
Show answer
(b) Segmentation is external and internal with serial repetition, and circulation is closed.
Annelid metamerism includes external and internal segmentation with serial repetition of some organs. Their circulatory system is closed, with blood moving through vessels.
Arthropod and mollusc body plans
Question 9
A learner writes, ‘A scorpion is not an arthropod because it is not an insect. True arthropods have a calcareous covering and closed circulation.’ Which correction is fully correct?
(a)A scorpion is a non-insect arthropod with a calcareous exoskeleton and open circulation
(b)A scorpion is a non-insect arthropod with a chitinous exoskeleton and open circulation
(c)A scorpion is a non-insect arthropod with a chitinous exoskeleton and closed circulation
(d)A scorpion is not an arthropod because all arthropods are insects, though they have chitin and open circulation
Show answer
(b) A scorpion is a non-insect arthropod with a chitinous exoskeleton and open circulation
A scorpion is an arthropod even though it is not an insect. Arthropods have a chitinous exoskeleton, jointed appendages, and open circulation.
Question 10
Locust, butterfly, scorpion, and prawn are compared as arthropods. Which statement gives the correct shared phylum pattern?
(a)They include insect and non-insect forms, have a chitinous exoskeleton, and have closed circulation
(b)They include insect and non-insect forms, have a calcareous exoskeleton, and have open circulation
(c)Only the locust and butterfly are arthropods because every arthropod is an insect
(d)They include insect and non-insect forms, have a chitinous exoskeleton, and have open circulation
Show answer
(d) They include insect and non-insect forms, have a chitinous exoskeleton, and have open circulation
These examples show that Arthropoda extends beyond insects. Arthropods share jointed appendages and a chitinous exoskeleton, and they have an open circulatory system.
Echinoderm and hemichordate diagnostics
Question 11
A learner writes, ‘Echinoderms are radial as adults and larvae, and their water vascular system removes body wastes.’ Which correction is complete?
(a)Adults are bilateral, larvae are radial, and the water vascular system is the closed circulatory system
(b)Adults are radial, larvae are bilateral, and the water vascular system is not an excretory system
(c)Adults are radial and larvae are bilateral, but the water vascular system is the excretory system
(d)Adults and larvae are both radial, but the water vascular system is not an excretory system
Show answer
(b) Adults are radial, larvae are bilateral, and the water vascular system is not an excretory system
Only the adult is radially symmetrical; the larva is bilaterally symmetrical. The water vascular system aids locomotion, food capture and transport, and respiration, while an excretory system is absent.
Question 12
Which statement correctly relates echinoderm symmetry and the water vascular system?
(a)Adults and larvae are both radial, and the water vascular system supports locomotion, feeding, and respiration
(b)Adults are bilateral, larvae are radial, and the water vascular system pumps blood through closed vessels
(c)Adults are radial, larvae are bilateral, and the water vascular system supports locomotion, feeding, and respiration
(d)Adults are radial, larvae are bilateral, and the water vascular system is the excretory system
Show answer
(c) Adults are radial, larvae are bilateral, and the water vascular system supports locomotion, feeding, and respiration
Echinoderm adults are radial and larvae are bilateral. The water vascular system assists locomotion, food capture and transport, and respiration; an excretory system is absent.
Tetrapod classes: Amphibia, Reptilia, Aves, and Mammalia
Question 13
A student makes four claims:
1. An ostrich is not a bird because it cannot fly. 2. Bird air sacs replace lungs. 3. Every mammal gives birth to young. 4. A flying fox is a bird.
Which diagnosis is correct?
(a)Only the ostrich claim is correct because every bird must fly.
(b)Only the respiratory claim is correct because air sacs replace bird lungs.
(c)All four claims must be corrected using feathers, lung respiration, the oviparous mammal exception, and mammalian diagnostic traits.
(d)The mammal claims are correct because every mammal is viviparous and flying mammals leave Mammalia.
Show answer
(c) All four claims must be corrected using feathers, lung respiration, the oviparous mammal exception, and mammalian diagnostic traits.
All four claims need correction. An ostrich is a bird despite being flightless. Birds exchange gases in their lungs; air sacs help ventilate those lungs. Mammals include egg-laying exceptions such as the platypus. A flying fox (Pteropus) is a bat and belongs to Mammalia, with mammalian traits such as hair and mammary glands.
Claim
Correction
Ostrich is not a bird
It is a flightless bird
Air sacs replace lungs
Lungs exchange gases; air sacs support ventilation
Every mammal gives birth to young
Platypus and echidnas lay eggs
Flying fox is a bird
It is a mammal (a bat)
Question 14
An animal spends part of its life in water and part on land, has moist scaleless skin, two pairs of limbs, a three-chambered heart, external fertilisation, and indirect development. Which conclusion is best?
(a)It is a reptile because all tetrapods with limbs have dry scaly skin.
(b)It is a fully aquatic fish because any vertebrate associated with water belongs to Pisces.
(c)It is a bird because a three-chambered heart is characteristic of Aves.
(d)It is an amphibian; aquatic association alone does not make it a fish.
Show answer
(d) It is an amphibian; aquatic association alone does not make it a fish.
The combined traits identify an amphibian, not a fish. Amphibians can use both aquatic and terrestrial habitats and differ from fishes in limbs, skin, heart, and development.
Cyclostomes, cartilaginous fishes, and bony fishes
Question 15
Which comparison correctly states fertilisation in cartilaginous and bony fishes?
(a)Chondrichthyes have internal fertilisation, whereas Osteichthyes usually have external fertilisation.
(b)Both classes have external fertilisation because all fishes release gametes into water.
(c)Both classes have internal fertilisation because all fishes share one fertilisation pattern.
(d)Chondrichthyes have external fertilisation, whereas Osteichthyes usually have internal fertilisation.
Show answer
(a) Chondrichthyes have internal fertilisation, whereas Osteichthyes usually have external fertilisation.
Chondrichthyes have internal fertilisation. Fertilisation in Osteichthyes is usually external, so the same pattern cannot be assigned to both classes.
Do wings and a streamlined shape make bats and birds one animal class?
Wrong
A bat belongs in the same animal class as birds because both fly with wings.
Why it feels right. Flight is the most visible feature, so I use it as the deciding trait.
Right
Classification uses a set of defining features. Similar functions can appear in different groups.
Worked example
Bat
Wings→Hair and milk→Mammal
Bird
Wings→Feathers→Bird
Both fly, but their defining traits lead to different classes.
A bat has hair and nurses its young, characteristic mammalian features.
A bird has feathers.
Both have forelimbs adapted for flight, yet they belong to different vertebrate classes.
Cookies
We use cookies, including Meta’s and, if a ChatGPT advert brought
you, OpenAI’s, to see how visitors find us.
They are never used on your child’s screens in the app. You can turn them
off here, and change your mind any time.
Privacy policy
