29 reviewed questions with answers and explanations.
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Seed plants are divided into
B: angiosperms and gymnosperms
Seed plants include gymnosperms, whose ovules are not enclosed in ovaries, and angiosperms, the flowering plants. Both groups reproduce using seeds, unlike ferns and bryophytes.
AI-reviewed · source checkedWhich gas is evolved from the sugar-and-yeast mixture in the apparatus?
The apparatus is used to demonstrate which process?
Which of the following can cause shrinkage of living cells?
D: Hypertonic solution
A hypertonic solution draws water out of a cell by osmosis and can cause the cell contents to shrink. A hypotonic solution instead favours water entry, while an isotonic solution causes no net osmotic change.
AI-reviewed · source checkedWhich statement describes mammalian leucocytes?
C: they are large and nucleated
Leucocytes are nucleated white blood cells involved in defence. They are generally larger than red blood cells, which are far more numerous in normal mammalian blood and lack nuclei when mature.
AI-reviewed · source checkedThe conversion of a nutrient into a molecule in the body of a consumer is referred to as
B: assimilation
Assimilation incorporates absorbed nutrients into the body’s own materials. Digestion breaks food down, while absorption transfers digested molecules across the intestinal lining before they can be used by cells.
AI-reviewed · source checkedThe ability of living organism to detect and respond to changes in the environment is referred to as
B: irritability
Irritability is the capacity to detect and respond to stimuli. A response need not involve movement of the whole organism; growth, secretion or another physiological change can also be a response.
AI-reviewed · source checkedAn example of an endospermous seed is
A: maize grain
A maize grain retains a substantial endosperm that stores nutrients for the developing seedling. In many other seeds, the cotyledons absorb most of that storage tissue before the seed matures.
AI-reviewed · source checkedThree tubes contain sucrose: I, sucrose and water; II, sucrose and dilute acid; III, sucrose and its hydrolysing enzyme. Under suitable laboratory conditions, which tubes produce detectable glucose after catalysed hydrolysis?
B: II and III only
Dilute acid or the appropriate enzyme can hydrolyse sucrose into glucose and fructose. Water alone does not appreciably hydrolyse sucrose during the usual laboratory test period, so tubes II and III are positive.
AI-reviewed · source checkedWhich enzyme hydrolyses the cane sugar (sucrose) in the test-tube experiment?
C: sucrase
Sucrase hydrolyses sucrose into glucose and fructose. Maltase acts on maltose, whereas the protein-digesting enzymes in the other choices do not split the sucrose glycosidic bond.
AI-reviewed · source checkedThe path followed by air as it passes through the lungs in mammals is
A: trachea → bronchi → bronchioles → alveoli
Inhaled air passes down the trachea into bronchi, then progressively smaller bronchioles and finally the alveoli. The alveoli provide a large thin surface for exchange with pulmonary capillary blood.
AI-reviewed · source checkedThe movement response of a cockroach away from a light source can be described as
B: negative phototaxism
Movement away from light is negative phototaxis. Taxis is directional movement of an organism relative to a stimulus; tropism usually describes a directional growth response, particularly in plants.
AI-reviewed · source checkedThe vascular tissues in higher plants are responsible for
A: the movement of food and water
Xylem transports water and mineral ions, while phloem distributes sugars and other organic solutes. Together these vascular tissues connect sources, storage organs and growing parts of the plant.
AI-reviewed · source checkedWhich of the following organs regulates the levels of water, salts, hydrogen ions and urea in the mammalian blood?
B: Kidney
The kidneys filter blood and adjust tubular reabsorption and secretion. These processes regulate water, electrolytes and acid-base balance while allowing nitrogenous wastes such as urea to leave in urine.
AI-reviewed · source checkedThe usual one-way flow of water for gas exchange in a bony fish is
D: mouth → gills → operculum
In a typical bony fish, water enters the mouth, passes over the gills and exits through the opercular openings. Oxygen diffuses from this water into blood across the thin gill surfaces.
AI-reviewed · source checkedThe asexual process commonly used by Paramecium and many other protists is
D: fission
Paramecium commonly reproduces asexually by binary fission, dividing into two daughter cells. Fission also occurs in many other protists, although protist reproductive strategies are diverse.
AI-reviewed · source checkedThe interaction of a community of organisms with its abiotic environment constitutes
C: an ecosystem
An ecosystem includes a community of organisms and the nonliving environment with which they interact. It therefore includes both biological relationships and physical conditions such as water and temperature.
AI-reviewed · source checkedThe vector of the malaria parasite is
B: female Anopheles mosquito
Female Anopheles mosquitoes transmit human malaria parasites when they take blood meals. Male mosquitoes do not take blood meals and are not the vectors in this transmission cycle.
AI-reviewed · source checkedWhich of the following instruments is used to measure relative humidity?
C: Hygrometer
A hygrometer measures humidity, including relative humidity. Relative humidity compares the water vapour present with the amount needed for saturation at the same temperature.
AI-reviewed · source checkedThe initial exo-erythrocytic multiplication of human malaria parasites occurs in the
A: liver of humans
Before infecting red blood cells, malaria sporozoites invade liver cells and develop there. This liver stage is termed exo-erythrocytic because it occurs outside erythrocytes.
AI-reviewed · source checkedThe broad division of habitats into water and land environments is
B: aquatic and terrestrial
A broad habitat division separates water environments, aquatic habitats, from land environments, terrestrial habitats. Each category can be divided further into more specific environments.
AI-reviewed · source checkedDracunculiasis can be acquired by
B: drinking contaminated water
People can acquire Guinea worm infection by drinking water containing infected tiny crustaceans called copepods. Swallowing the intermediate host allows the parasite to enter the human body.
AI-reviewed · source checkedWhich group contains common density-dependent influences on a population?
C: Food limitation, predation, disease and accumulation of metabolites
Food limitation, predation, disease and waste accumulation can become more important as population density rises. Their effects depend on biological interactions and the number of organisms sharing resources.
AI-reviewed · source checkedA heritable character determined by a gene on the X chromosome is described as
B: sex-linked
A gene on the X chromosome is X-linked, a type of sex linkage. Its allele can be dominant or recessive, so chromosomal location is a separate concept from dominance.
AI-reviewed · source checkedCrowding in a population can increase the risk of
C: disease rate
Crowding can increase contact between individuals and facilitate the spread of infectious agents. The outcome depends on the pathogen and conditions, but increased disease transmission is a common density-dependent effect.
AI-reviewed · source checkedAt a single flower-colour locus, crossing true-breeding red and white plants produces pink heterozygotes. This illustrates
B: incomplete dominance
Incomplete dominance produces a heterozygous phenotype intermediate between the two homozygotes, such as pink flowers from red and white parental lines. Both alleles remain distinct rather than permanently blending.
AI-reviewed · source checkedThe crossing of individuals of the same species with different genetic characters is
A: cross-breeding
Cross-breeding combines individuals from genetically different lines or varieties within a species. It can combine useful traits, whereas inbreeding mates closely related individuals.
AI-reviewed · source checkedHow many alleles occur in the standard model of human ABO blood-group inheritance?
A: 3
The usual ABO inheritance model has three alleles in the population: IA, IB and i. Each person normally carries two of these, producing the familiar A, B, AB or O phenotypes.
AI-reviewed · source checkedThe independent evolution of wings for powered flight in birds and bats illustrates
A: convergent evolution
Bird and bat wings evolved independently as flight structures. Their underlying forelimbs are homologous through shared vertebrate ancestry, but the independent acquisition of wings for powered flight illustrates convergence.
AI-reviewed · source checked