27 reviewed questions with answers and explanations.
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The mouthparts of an adult housefly are adapted for
A: Lapping and sponging
An adult housefly takes in liquid food using sponging mouthparts. Saliva can help dissolve suitable solid food before it is taken up. Its mouthparts do not chew solid pieces or pierce skin like those of a biting fly.
AI-reviewed · source checkedMosses, liverworts and ferns can be grouped together because they
C: Are seedless plants
All three reproduce without seeds. Ferns have vascular tissues and distinct organs, whereas mosses and liverworts are bryophytes. Their habitats vary, and none produces flowers.
AI-reviewed · source checkedWhich of the following invertebrates does NOT possess antennae?
E: Spider
Spiders are arachnids and have no antennae. Their pedipalps and sensory hairs perform sensory functions. Insects, centipedes and millipedes have one pair of antennae, while crustaceans typically have two pairs.
AI-reviewed · source checkedWhich statement is INCORRECT about the typical green, heart-shaped prothallus of a homosporous fern? It
C: Is the dominant plant generation
The prothallus is the small gametophyte that bears the sex organs. The much larger leafy fern is the dominant sporophyte generation. A typical free-living prothallus is green and attached to its substrate by rhizoids.
AI-reviewed · source checkedWhich cell constituent is not normally present in animal cells but is present in photosynthetic plant cells?
B: Chloroplasts
Chloroplasts carry out photosynthesis in green plant cells. Typical animal cells do not have chloroplasts. Mitochondria, ribosomes and Golgi apparatus occur in both groups, and animal cells can also contain small vacuolar compartments.
AI-reviewed · source checkedIn a placental mammal, which organ provides the main exchange surface for oxygen and nutrients between the mother and the developing offspring?
E: Placenta
The placenta is the main exchange organ between maternal and fetal circulations. Oxygen and nutrients cross its exchange surface and reach the fetus through the umbilical circulation. Maternal and fetal blood normally remain in separate circulations.
AI-reviewed · source checkedAt equal pressure, osmosis between dilute solutions separated by a membrane permeable to water but not the solute is the net movement of
D: Water across the membrane from lower to higher solute concentration
Water moves from the more dilute solution, which has higher water potential, towards the more concentrated solution through the selectively permeable membrane. The direction stated assumes equal pressure and a solute that cannot cross the membrane.
AI-reviewed · source checkedIn the usual stabilising role of a fish’s dorsal and anal fins, they chiefly help with
B: Controlling rolling movement
Dorsal and anal fins help stabilise the fish and resist unwanted rotation such as rolling. Their contribution varies with species and swimming behaviour. Other fins can assist steering, while buoyancy depends on body density and, in many bony fish, a swim bladder.
AI-reviewed · source checkedA jointed arthropod exoskeleton is NOT found in the
C: Earthworm
An earthworm is an annelid supported mainly by a hydrostatic skeleton. The other animals are insects or insect larvae and have an external cuticle that is shed during growth. A soft-bodied larva can still possess an exoskeleton.
AI-reviewed · source checkedWhich blood component forms the initial plug at a damaged vessel and helps the clotting process?
B: Platelets
Platelets adhere at a damaged vessel and aggregate to form a temporary plug. They also support reactions that lead to a fibrin clot. Coagulation involves plasma factors as well as platelets; it is not caused simply by blood touching air.
AI-reviewed · source checkedPepsin is a digestive enzyme that breaks down
C: Proteins into smaller peptides
Pepsin begins protein digestion in the acidic stomach, cleaving proteins into smaller peptide fragments. It does not digest cellulose, fats or sucrose. Further protein digestion takes place in the small intestine.
AI-reviewed · source checkedAlcoholic fermentation of glucose by yeast produces
A: Carbon dioxide and ethanol
Yeast converts pyruvate into acetaldehyde, releasing carbon dioxide, and then reduces acetaldehyde to ethanol. This regenerates NAD⁺ so glycolysis can continue without oxygen. Carbon dioxide also helps bread dough rise.
AI-reviewed · source checkedIn the Biuret test, protein is mixed with sodium hydroxide solution. Which chemical is then added for a positive reaction?
B: Copper sulphate
Copper(II) ions in alkaline solution interact with peptide bonds to produce a violet colour. Copper sulphate supplies these ions, while sodium hydroxide provides the alkaline conditions. The result indicates peptide bonds rather than a particular protein identity.
AI-reviewed · source checkedLoss of pancreatic digestive secretions would impair digestion of which combination of food substances?
B: Starch, proteins and fats
Pancreatic juice supplies amylase for starch, proteases for proteins and lipase for fats. Losing these secretions can therefore impair digestion of all three groups. Other digestive secretions may still act, so impaired digestion does not mean every digestive process stops.
AI-reviewed · source checkedWhich region normally has the same number of vertebrae in a rabbit, rat and human?
D: Cervical
Rabbits, rats and humans normally have seven cervical vertebrae. This is the neck region, including the atlas and axis. The numbers in the thoracic, lumbar, sacral and caudal regions differ between these animals.
AI-reviewed · source checkedIn the usual angiosperm model, how many nuclei are present in the mature pollen tube after generative-cell division but before discharge, while the tube nucleus remains intact?
B: 3
The generative cell divides to form two sperm cells, each with a nucleus. Together with the vegetative tube nucleus, this gives three nuclei. The count refers to this defined stage, before the sperm are discharged for double fertilisation.
AI-reviewed · source checkedWhich part of a vertebrate brain is especially associated with coordination of muscular activity and balance?
D: Cerebellum
The cerebellum helps coordinate movement, timing and balance by comparing intended movement with sensory feedback. It works with other parts of the nervous system rather than acting alone. Well-coordinated movement is therefore especially associated with cerebellar function.
AI-reviewed · source checkedWhich adaptation is primarily associated with swimming rather than bird flight?
E: Webbed feet
Webbed feet spread the force of a backward stroke over a larger area of water, aiding swimming. Streamlining, strong flight muscles, a suitable sternum and reduced mass can support flight. A swimming bird may also fly, but the webbing is chiefly a swimming adaptation.
AI-reviewed · source checkedWhat spatial pattern is most directly recorded by a line transect in an ecological survey?
C: The distribution of organisms along a line
A line transect records organisms or vegetation encountered along a selected line. It can show how occurrence changes across a habitat or environmental gradient. Estimating the total population of a whole habitat requires an appropriate sampling design and further analysis.
AI-reviewed · source checkedIn the usual forward flow through a systemic vascular bed, blood does NOT flow from
D: Arterioles back into the supplying artery
Blood normally travels from arteries into smaller arterioles, through capillaries, then into venules and veins. Flow back from arterioles into their supplying artery reverses this usual sequence. Local pressure changes and pathological reverse flow are outside this normal-flow comparison.
AI-reviewed · source checkedThe axial skeleton of a mammal does not include the bones of the
C: Limbs
The axial skeleton includes the skull and vertebral column, including cervical, trunk and caudal regions where present. Limb bones belong to the appendicular skeleton together with their supporting girdles. The limbs are therefore the exception.
AI-reviewed · source checkedGreen plants support food webs chiefly through their role as
B: Producers
Photosynthetic plants use light energy to make organic compounds from carbon dioxide. This primary production supplies food and stored chemical energy to many other organisms in a food web. Plants also respire, but that does not remove their producer role.
AI-reviewed · source checkedAn anemometer is an instrument for measuring
C: Wind speed
An anemometer measures wind speed. A wind vane instead indicates wind direction. Relative humidity, water turbidity and salinity require different instruments or methods.
AI-reviewed · source checkedWhich is a normal major component of clean air rather than an air pollutant at its usual atmospheric proportion?
E: Molecular nitrogen
Molecular nitrogen makes up about 78% of dry air and is a normal atmospheric constituent. This differs from reactive nitrogen compounds that can contribute to pollution. Smoke, sulphur dioxide and carbon monoxide are pollutants, while excessive noise is environmental pollution.
AI-reviewed · source checkedWhich group consists entirely of abiotic environmental factors?
C: Wind, altitude, humidity and light
Abiotic factors are nonliving physical or chemical features of the environment. Wind, altitude, humidity and light all fit that description. Plankton, insects, conifers and bacteria are living organisms and are biotic components.
AI-reviewed · source checkedWhich disease, cause, symptom and transmission combination is correct?
D: Smallpox — virus — blister-like skin lesions — close contact with an infected person
Smallpox was caused by variola virus and could spread through close contact, producing characteristic skin lesions. Cholera and syphilis are bacterial diseases. Malaria and sleeping sickness are caused by protozoan parasites, with mosquito and tsetse-fly transmission respectively.
AI-reviewed · source checkedWhich sequence orders water-erosion forms from removal across a broad surface towards progressively larger channels?
D: Sheet → rill → gully
Sheet erosion removes soil across a relatively broad surface. Concentrated runoff can cut small rills, and larger channels are called gullies. This is a sequence of increasing channel development, not a rule that every site must pass through every stage.
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