All 40 questions from the Joint Admissions and Matriculation Board (JAMB) Biology 2019 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Benedict's solution is used to test for
Benedict's solution tests for the presence of reducing sugars. An orange-red precipitate indicates a reducing sugar is present. (Lipids are tested with the osmic acid or transparency test; proteins with the Biuret, Millon's, or xanthoproteic test.)
A group of populations that interact in a given habitat can be described as
A group of populations that interact together in a given habitat constitutes a community. (Biosphere encompasses hydrosphere, atmosphere and lithosphere; a biome is a large natural terrestrial ecosystem.)
At times, hyenas feed on remains of animals killed by other animals. At other times, hyenas themselves kill animals for food. Therefore, hyenas may best be described as
Scavengers feed on remains of dead animals; predators kill other animals directly for food. Hyenas do both.
Which of the animals below is poikilothermic?
Poikilothermic (cold-blooded) animals have a body temperature that varies with the surrounding. Fishes, amphibians (e.g. toad) and reptiles are poikilothermic; mammals and birds (dove, lion, chicken) are homoiothermic (warm-blooded).
The process which ensures that the chromosome number for each species of organisms remains constantly from generation to generation is called
Meiosis produces daughter cells with half the parent's chromosome number (reductional division), which is restored at fertilization, keeping the species' chromosome number constant across generations. (Note: the source key states the answer as (c) mitosis; biologically this role is typically attributed to meiosis — flagged as a possible key inconsistency.)
Which of the following is not part of the whorls of a flower?
Antheridium is not a whorl of a flower; it is the male sex organ of non-flowering plants (the female organ being the archegonium).
In man, the thoracic region of the vertebral column is made up of how many vertebrae?
A man has twelve thoracic vertebrae (compared to 7 cervical, 5 lumbar, 5 sacral, and 4 caudal).
Plants which can survive in places where water supply is limited are called
Xerophytes survive in places with limited water supply (e.g. Cactus, Euphorbia, Aloe). Mesophytes need adequate water supply; hydrophytes live in fresh water.
Which of the following has a four-chambered heart?
Mammals (like the rat) and birds have four-chambered hearts (two auricles, two ventricles). Fish have two-chambered hearts; amphibians have three chambers.
Which of the following enzymes curdles milk?
Renin curdles milk by converting soluble caseinogens into insoluble casein. (Pepsin converts proteins to peptones; ptyalin hydrolyses starch to maltose.)
All of the following are modified roots except
Prop, buttress, and climbing roots are all modified (adventitious/specialised) roots. A tap root is the main root developed from the radicle, not a modification.
Which of the following is a polysaccharide?
A polysaccharide contains many monosaccharide units linked by glycosidic bonds. Glucose, fructose and galactose are monosaccharides; cellulose is a polymer of glucose.
The end of each molecule of phospholipids that is soluble in water is said to be
Phospholipids are amphipathic: the hydrophilic end has affinity for water, while the hydrophobic end has little affinity for water.
The type of association in which both organisms cannot live without the other is called
In mutualism, both organisms benefit from and depend on each other for survival. (In parasitism one benefits while the other suffers harm; in commensalism one benefits while the other is unaffected.)
Which of the following can be used in place of baking powder?
Yeast (Saccharomyces cerevisiae) can be used in place of baking powder, as it makes flour rise through releasing CO₂ during anaerobic respiration.
Which of the following is not a direct consequence of the green house effect?
The greenhouse effect increases retention of the sun's radiant energy, caused by gases such as water vapour, carbon dioxide, nitric oxide, methane and CFCs, leading to global warming, melting ice caps, and rising land temperatures. Water pollution is not a direct consequence.
Which of the following parts of the leaf possesses air spaces?
The mesophyll (between the upper and lower epidermis) is divided into the tightly-packed palisade mesophyll (main site of photosynthesis) and the loosely-arranged spongy mesophyll, which functions in gaseous diffusion via its air spaces.
Which of the following organisms possesses the homodont dentition?
In homodont dentition, all teeth are similar in shape/size/function; in heterodont dentition, teeth differ. Mammals (rat, cat, man) possess heterodont dentition; the lizard, a reptile, possesses homodont dentition.
Which of the following arthropods lacks antennae?
Arachnids (e.g. tick, scorpion, spider) are the only arthropods that lack antennae.
If a red blood cell is placed in hypertonic solution for a while, the cell will become
In a hypertonic solution, a red blood cell loses water and shrinks — this is called crenation.
Which of the following glands secretes a substances into the bloodstream?
Hormones are secreted by endocrine glands (e.g. adrenal, pituitary, thyroid, parathyroid) directly into the bloodstream. Gastric, salivary and tear glands are exocrine glands, not endocrine.
During blood transfusion, agglutination may occur as a result of the reaction between
Agglutination occurs between contrasting (matching/reactive) antigens and antibodies. If a person with blood type A is transfused with type B blood, the antibody-B in the recipient's blood attacks the antigen in the donor's type B blood.
Which of the following substances is/are able to diffuse through the mother's blood into the blood of the foetus?
The foetus receives glucose and oxygen from the mother through the placenta. The placenta removes excretory wastes (urea, carbon dioxide) from the foetus's blood into the mother's blood for elimination.
If the cerebellum of a person is slightly damaged, which of the following will be impaired?
The cerebellum's major function is maintaining balance and posture; slight damage impairs walking.
Which of the following is likely to have a higher concentration of mitochondria?
The number of mitochondria in a cell depends on how metabolically active it is; a very active cell like the sperm cell contains a large number of mitochondria.
The liver performs all the following functions except
The liver regulates body heat, breaks down worn-out red blood cells, manufactures vitamin A, regulates blood sugar, stores iron, and forms red blood cells in embryos — but it does not form cholesterol as one of its standard listed functions here.
The type of storage organ found in ginger is called
A rhizome is a horizontal underground stem capable of producing shoot and root systems; ginger, turmeric, and asparagus are examples of plants with rhizomes used as storage organs.
Pest can be controlled without subsequent danger of polluting the eco-system by
Introducing or increasing the population of a pest's natural enemy is a biological method of pest control that avoids the pollution risk of chemical pesticides.
Which of the following represents the Watson-Crick DNA base pair model?
Guanine pairs with cytosine (G-C) while thymine pairs with adenine (T-A) in the Watson-Crick DNA model.
Which of the following infections is unlikely to respond to antibiotics treatment?
Measles is caused by a paramyxovirus, which is not susceptible to antibiotics (antibiotics target bacteria, not viruses).
Prokaryotic cells are found in
Prokaryotic cells are found in monerans; bacteria and blue-green algae are examples of monerans.
If two parents are sickle cell carriers then their genotypes would be
A sufferer of sickle cell disease/trait has genotype HbᴬHbˢ (carrier); a normal person has HbᴬHbᴬ. If both parents are carriers, both have genotype HbᴬHbˢ.
The correct order of classification of human being is
Classification order: Kingdom→Phylum→Sub-phylum→Class→Order→Family→Genus→Species. For humans: Animalia→Chordata→Vertebrata→Mammalia→Primate→Hominidae→Homo→Sapiens.
The botanical name for yellow yam is a
Yellow yam is Discorea cayenensis. (White yam is D. rotundata; water yam is D. alata; aerial yam is D. bulbifera; Chinese yam is D. esculenta.)
The hormone which tones up the muscles of a person in time of danger is from
Adrenalin (the emergency hormone), which tones up muscles in time of danger, is produced from the adrenal glands situated on top of the kidneys.
When two opposite genes for the same character contained in the same individual, the character that shows is known as
When two opposite (alternative) genes for a character are present in an individual, the trait expressed is dominant, while the one that fails to be expressed is recessive.
During anaerobic respiration, the products obtainable are
Anaerobic respiration in plants yields ethanol and carbon dioxide (in animals, lactic acid): C₆H₁₂O₆ → 2CO₂ + 2C₂H₅OH.
Which of the following bones belong to the appendicular skeleton?
The axial skeleton comprises the skull, vertebral column and sternum. The appendicular skeleton comprises the bones of the limbs, including the ulna.
The formation of fruit without fertilization is known as
Formation of fruit without fertilization is parthenocarpy. (The equivalent process in animals — development without fertilization — is parthenogenesis.)
Which of the following is not a form of placentation?
Types of placentation (arrangement of ovules in the ovary) include marginal, parietal, free-central, axile, and basal. Ovulation is a different reproductive process, not a form of placentation.
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