30 reviewed questions with answers and explanations.
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Which of the following is the lowest category of classification?
B: Species
Species is the lowest rank among class, family, genus and species. A genus contains related species; families contain genera, and classes are still broader groupings.
AI-reviewed · source checkedPlants that show secondary growth are usually found among the
D: dicotyledons
Typical secondary growth in many dicots increases stem and root girth through lateral meristems. Vascular cambium adds secondary vascular tissues, and cork cambium contributes the outer protective covering.
AI-reviewed · source checkedAn animal body divisible into similar halves by multiple planes through its central axis has which specific type of symmetry?
A: radially symmetrical
Radial symmetry arranges body parts around a central axis so several planes through that axis divide the body into similar halves. Bilateral symmetry instead has one principal left-right plane.
AI-reviewed · source checkedWhich of the following possesses mammary gland?
B: whale
Whales are mammals and females produce milk in mammary glands to nourish their young. The other listed animals are fishes and do not possess mammary glands.
AI-reviewed · source checkedCountershading is an adaptive feature that enables animals to
B: remain undetected
Countershading commonly makes an animal darker above and lighter below. This can reduce visual contrast or the appearance of shadow, helping the animal escape detection in its surroundings.
AI-reviewed · source checkedWhich young plant organ normally lacks a waterproof epidermal cuticle in its water-absorbing region?
C: root
Young absorbing roots generally lack the thick waterproof cuticle found on aerial organs. This permits water and dissolved minerals to enter; older roots may develop other protective barriers.
AI-reviewed · source checkedIn the mammalian male reproductive system, the part that serves as a passage for both urine and semen is the
A: urethra
The male urethra carries urine from the bladder and also carries semen during ejaculation. The ureters conduct urine from the kidneys to the bladder and do not carry semen.
AI-reviewed · source checkedWhich listed element is a universally recognised essential plant micronutrient?
A: Copper
Copper is an essential plant micronutrient needed in small quantities, including for enzyme activity. Potassium and phosphorus are macronutrients required in larger quantities.
AI-reviewed · source checkedWhich of the following organisms is both parasitic and autotrophic?
B: Loranthus
Loranthus is a photosynthetic hemiparasite: it can make organic food while obtaining water and mineral resources from a host. Sundew captures insects but is not a parasitic plant on a host.
AI-reviewed · source checkedWhich of the following is a polysaccharide?
D: Cellulose
Cellulose is a polysaccharide made of many glucose units joined in long chains. Glucose is a monosaccharide, while sucrose and maltose each contain two sugar units and are disaccharides.
AI-reviewed · source checkedIn the mammalian kidney, glomerular ultrafiltrate first enters the space in
B: Bowman's capsule
Ultrafiltrate crosses the glomerular filtration barrier into the capsular space of Bowman’s capsule. This is the first stage of urine formation, before tubular reabsorption and secretion modify the filtrate.
AI-reviewed · source checkedWhich option names both lateral meristems responsible for typical secondary growth in woody plants?
C: Vascular cambium and cork cambium
Vascular cambium produces secondary xylem and phloem, while cork cambium contributes the protective periderm. Together these lateral meristems account for typical secondary growth of woody stems and roots.
AI-reviewed · source checkedAn example of a fruit that develops from a single carpel is
C: bean
A bean pod is a legume that develops from a single carpel. It typically opens along two seams at maturity, whereas tomato, orange and okra ovaries contain multiple fused carpels.
AI-reviewed · source checkedThe autonomic nervous system can adjust the
B: heart beat
Autonomic nerves adjust heart rate and other involuntary functions. The heart has its own pacemaker activity, while autonomic input changes the rate and force of contraction to suit bodily needs.
AI-reviewed · source checkedWhich tropical vegetation zone has cooler high-altitude conditions suitable for some plants of temperate origin?
D: montane forest
Tropical mountains have cooler conditions than nearby lowlands. Suitable montane environments can therefore support some plants of temperate origin, provided their other soil and moisture requirements are met.
AI-reviewed · source checkedWhich pair of physical processes transfers water to atmospheric vapour and converts that vapour back into droplets?
B: evaporation and condensation of water in the environment
Evaporation transfers water into the atmosphere, and condensation forms droplets that can return as precipitation. Runoff, infiltration and biological processes also contribute to the full water cycle.
AI-reviewed · source checkedOrganisms living in an estuarine habitat are adapted to
C: withstand wide fluctuations in salinity
Estuaries mix river water with seawater, so salinity can change with tides and freshwater flow. Resident organisms often tolerate a wider salinity range than species restricted to stable freshwater or marine conditions.
AI-reviewed · source checkedStilt roots, pneumatophores and salt-management structures occur among plants adapted to
B: mangrove swamps
Mangrove habitats combine waterlogged, often oxygen-poor soils with saline conditions. Different mangrove species have adaptations such as aerial roots, supportive roots or mechanisms for managing salt.
AI-reviewed · source checkedThe most likely first colonizers of a bare rock are
C: lichen
Lichens can colonise exposed rock and contribute to weathering and accumulation of organic material. They are typical pioneer organisms in primary succession, helping make later colonisation possible.
AI-reviewed · source checkedIn the simple logistic model, when population size reaches carrying capacity, its size tends to
D: remain steady
At carrying capacity in the simple logistic model, population size is approximately stable because net population growth is zero. Growth slows before the population reaches that level.
AI-reviewed · source checkedAn indigenous method of renewing and maintaining soil fertility is by
D: crop rotation and shifting cultivation
Crop rotation can replenish or conserve nutrients, and a sufficiently long fallow in shifting cultivation can allow soil fertility to recover. Their effectiveness depends on the crops, land pressure and fallow duration.
AI-reviewed · source checkedThe diseases caused by water-borne pathogens include
D: typhoid and cholera
Typhoid and cholera can both spread through water contaminated with human faeces. Their causative bacteria differ, but unsafe water is an important transmission route for both diseases.
AI-reviewed · source checkedThe graph illustrates
For an X-linked recessive colour-vision trait, an affected man (XcY) and carrier woman (XCXc) have a child. What is the probability that the child is affected?
B: 50%
For XcY × XCXc, the equally likely children are XCXc, XcXc, XCY and XcY. Two of these four combinations express the recessive colour-vision trait, giving a probability of 50%.
AI-reviewed · calculation checkedThe correct base pairing for DNA is
A: adenine → thymine and guanine → cytosine
In ordinary double-stranded DNA, adenine pairs with thymine and guanine pairs with cytosine. These complementary pairs help preserve the sequence relationship between the two strands during replication.
AI-reviewed · source checkedA short, thick beak in a seed-eating bird is an adaptation for
A: crushing seeds
A short, stout beak can exert force to crack hard seeds. Nectar feeders instead tend to have more elongated feeding structures, while flesh-tearing birds commonly have hooked beaks.
AI-reviewed · source checkedThe basking of Agama lizards in the sun is to
B: raise their body temperature to become active
Agama lizards are ectotherms and can warm themselves by basking. Raising body temperature within a suitable range supports faster physiological activity and more effective movement.
AI-reviewed · source checkedA large number of reproductive termites in a nuptial swarm can help the species
B: ensure their perpetuation despite predatory pressure
Producing many winged reproductives increases the chance that some survive predators and establish colonies. Large numbers improve population persistence even though many individual termites fail to reproduce.
AI-reviewed · source checkedThe use and disuse of body parts and the inheritance of acquired traits were used to explain
B: Lamarck’s theory
Lamarck’s historical account linked use and disuse of organs to changes that he proposed could be inherited. Modern evolutionary explanations distinguish acquired changes in an individual from inherited genetic variation.
AI-reviewed · source checkedComparing the beak shapes of Galápagos finches is an example of
A: comparative anatomy
Comparing the forms of finch beaks is a comparison of anatomy. Such structural differences can be related to feeding ecology and adaptation, although Darwin’s evolutionary theory drew on much broader evidence.
AI-reviewed · source checked