JAMB Biology Previous Year Questions: 2021 | Biology for JAMB PDF Download

Q1: One of the functions of the xylem is?
(a) strengthening the stem
(b) manufacturing food
(c) reducing loss of water
(d) conducting manufactured food
Ans: (a)
Vascular tissue is comprised of the xylem and the phloem, the main transport systems of plants.
xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant and also provides physical support.

Q2: Which of the statements below is not characteristic of wind-pollinated flowers?
(a) Stigmas are usually large and feathery
(b) Nectary is usually absent
(c) The pollen grains have rough spiny surface
(d) The flowers are not scented.
Ans: (c)
Wind-pollinated flowers:

• No bright colors, special odors, or nectar.
• Small.
• Most have no petals.
• Stamens and stigmas exposed to air currents.
• Large amount of pollen.
• Pollen smooth, light, easily airborne.
• Stigma feathery to catch pollen from wind.

Q3: Some of the features of an animal are scales, teeth, nares, and backbone. The animal is likely to be a?
(a) toad
(b) bird
(c) lizard
(d) rat
Ans: (c)

• Cold-blooded ness;
• The teeth of reptiles are also less specialized in function than are mammalian teeth.
• A dry skin with scales but not feathers (a characteristic of birds) or hair (a characteristic of mammals);
• NB: Birds do not have teeth, although they may have ridges on their bills that help them grip food.
• Birds swallow their food whole, and their gizzard (a muscular part of their stomach) grinds up the food so they can digest it.

Q4: Choose the sequence which represents the correct order of organisms in a food chain
(a) Grass, snake, toad, grasshopper, hawk
(b) Grass, grasshopper, toad, snake, hawk
(c) Grass, grasshopper, snake, toad, hawk.
(d) Grass, snake, grasshopper, toad, hawk
Ans: (b)
The functional group in a food chain include:

• Primary producer ? Primary consumer ? Secondary consumer
• Grass, grasshopper, toad, snake, hawk

Q5: Flatworms and roundworms are said to be invertebrates because?
(a) they are small animals
(b) they can live inside the vertebrates
(c) some of them are unicellular
(d) they have no backbones
Ans: (d)

• The most familiar invertebrates include the Protozoa, Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Echinodermata, Mollusca and Arthropoda.
• Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord.

Q6: When a Spirogyra cell is immersed in a salt solution more concentrated than its cell sap, it?
(a) remains unchanged
(b) takes tip water and burst
(c) absorbs a little water
(d) loses water and shrivels
Ans: (d)
Exosmosis is the movement of water outside the cells when a cell is placed in a hypertonic solution.
The cell becomes flaccid by the movement of water outside.

Q7: Which of the following is NOT regarded as a pollutant on land or in the air?
(a) Smoke
(b) Nitrogen
(c) Noise
(d) Sulphur dioxide
Ans: (b)
Air Pollutants

• Carbon Monoxide.
• Lead.
• Nitrogen Oxides.
• Ozone.
• Particulate Matter.
• Sulfur Dioxide.
• Other Air Pollutants.

The primary pollutants of concern in land and soil are heavy metals, such as lead, mercury and others, pesticides and other persistent organic pollutants, and pharmaceuticals, such as antibiotics used for livestock management.

• Nitrogen (N), nonmetallic element of Group 15 [Va] of the periodic table.
• It is a colourless, odourless, tasteless gas that is the most plentiful element in Earth's atmosphere and is a constituent of all living matter.

Q8: The initial volume of water poured into a bag of dry soil was 50ml and the amount that drained through was 35mI. The percentage water content of the fully soaked soil is therefore?
(a) 46.7
(b) 25.0
(c) 20.0
(d) 30.0
Ans: (d)
Percentage of water content (retained) =

= 30%

Q9: When the original king and queen of termites die, they are replaced by
(a) the king and queen of another colony
(b) some adult reproductives from the same colony
(c) some adult workers which are specially fed to breed
(d) developing nymphs nurtured as secondary reproductives
Ans: (d)
When the queen dies, production of the blocking pheromone stops, and secondary reproductives may be produced.
In the Reticulitermes species, the queen and king may be replaced by numerous secondary reproductives, and the colony may become very large with the added productivity of many queens.

Q10: In demonstrating the importance of mineral elements in plants, the culture bottle must be darkened to?
(a) prevent algal growth in culture solution
(b) allow root growth
(c) prevent breakdown of mineral elements
(d) prevents photosynthesis in the root
Ans: (a)
Always use a completely opaque water storage tank - Algae uses photosynthesis to reproduce

Q11: In the mammalian respiratory system. exchange of gases occurs in the?
(a) lungs
(b) bronchi
(c) bronchioles
(d) alveoli
Ans: (d)
The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

Q12: Aged erythrocytes are destroyed in the?
(a) pancreas
(b) liver
(c) lymph nodes
(d) kidney
Ans: (b)
Together with the spleen, the liver breaks down worn out red blood cells (erythrocytes)

Q13: The villus in the small intestine is significant because it?
(a) increases the surface area for absorption
(b) increases the surface area for digestion
(c) assists in mixing digested food
(d) assists in filtering undigested food
Ans: (a)
The villi of the small intestine project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions.

Q14: Which of the following food substances will produce a brick-red colour when warmed with Benedict's solution?
(a) Glucose
(b) Starch
(c) Egg White
(d) Maltose
Ans: (a)
In lab, we used Benedict's reagent to test for one particular reducing sugar: glucose.
Benedict's reagent starts out aqua-blue. As it is heated in the presence of reducing sugars, it turns yellow to orange.

Q15: The blood vessel which carries blood from the alimentary canal to the liver is the?
(a) hepatic artery
(b) hepatic vein
(c) hepatic portal vein
(d) mesenteric artery
Ans: (c)
The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gall bladder, pancreas, and spleen to the liver.
This blood contains nutrients and toxins extracted from digested contents. 

Q16: Which of the following is TRUE of the process of conjugation in Paramecium?
(a) Micronucleus disintegrates
(b) Each ex-conjugant divides only once
(c) Macro nucleus undergoes division
(d) Each micronucleus divides twice
Ans: (d)

• In Paramecium, Conjugation is a form of sexual reproduction. It is a temporary union of two individuals of same species for mutual exchange of genetic materials.
• Through a process called conjugation, two paramecia line up side by side and then fuse together.
• The two paramecium separate and go on their way in their watery environment.
• They begin again to produce multiple copies of themselves through asexual fission.
• During sexual reproduction, the micronuclei of each paramecium undergo meiosis, ultimately halving the genetic content to create a haploid nucleus.
• These are exchanged between the two connected mates.
• The haploid nuclei from each mate fuse to create a new, genetically varied, micronucleus.

Q17: People who suck petrol with their mouths run the risk of increasing in their blood the concentration of
(a) iron
(b) lead
(c) calcium
(d) magnesium
Ans: (b)
It's discovered that tetraethyl lead (better known as lead) provided octane to gasoline, to fix knocking or pinging in engines that could damage them and waste gasoline.
Extremely high lead levels can lead to seizures, coma, and death.

Q18: Which of the following is a measure for the control of bilharzia?
(a) Cutting low bushes around homes
(b) Application of molluscicides in water bodies
(c) Screening windows and doors with mosquito nets
(d) Application of herbicides in water bodies
Ans: (b)

• Schistosomiasis, also known as bilharzia or 'snail fever', is a disease caused by parasites (worms called schistosomes) carried by freshwater snails.
• Schistosomiasis control focuses on reducing disease through periodic, large-scale population treatment with medication;
• a more comprehensive approach including potable water, adequate sanitation, and snail control would also reduce transmission.

Q19: The appendicular skeleton is composed of the pectoral girdle?
(a) pelvic girdle, fore and hind limbs
(b) pelvic girdle and fore limbs
(c) lumbar vertebrae and pelvic girdle
(d) lumbar vertebrae, fore and hind limbs
Ans: (a)
The appendicular skeleton includes the bones of the shoulder girdle, the upper limbs, the pelvic girdle, and the lower limbs.

Q20: A freshwater plant such as water lily can solve the problem of buoyancy by the possession of?
(a) aerenchyma tissues
(b) dissected leaves
(c) thin cell walls of the epidermis
(d) water-repelling epidermi
Ans: (a)

• Aerenchyma is found in hydrophytes like  water lily.
  This tissue encloses air and provides buoyancy to the plant parts

Q21: The correct sequence for the perception of smell in mammals is?
(a) chemicals → olfactory nerve endings → brain
(b) dissolved chemicals → nasal sensory cells → brain
(c) chemicals → mucus membrane sensory cells → brain
(d) dissolved chemicals → sensory cells → olfactory nerve → brain
Ans: (d)
In mammals(humans), the process of olfaction begins when volatile molecules enter the nasal cavity and activate receptors in the olfactory epithelium (OE). The olfactory receptor (OR) proteins are located in hair-like projections of the olfactory sensory neurons (OSNs).

Q22: I. High birth rate and high immigration rate
II. Low birth rate and high immigration rate
III. Low mortality rate and low emigration rate
IV. High mortality rate and high emigration rate.
Q. Which combination of the above can cause rapid over-crowding in climax biotic communities and human settlements?
(a) II and III
(b) I and III
(c) I and IV
(d) I and II
Ans: (b)
Low mortality rate, high birth rate, high immigration rate and low emigration rate are causes for rapid over-crowding.

Q23: The number of plant species obtained from a population study of a garden is as follows: Guinea grass (15), Ipomoea spp (5), Sida spp (7) and Imperata spp (23)

Q. What is the percentage of occurrence of Imperata spp?
(a) 35%
(b) 16%
(c) 46%
(d) 23%
Ans: (c)
No of  Imperata spp = 23
Total plant species = 50
Percentage of imperata spp = 25/50 x 100 ?
= 46%

Q24: When a marine fish was taken from the ocean and put in a tank of fresh water, it died after a short period because?
(a) the tank was too small compared to the large-ocean
(b) the body cells of the fish swelled and burst as a result of the hypotonic fresh water
(c) the body cells of the fish shrank as their sap was hypertonic to the freshwater
(d) there was no food in the tank, so the fish starved
Ans: (b)
Saltwater fish can't survive in freshwater because their bodies are highly concentrated of salt solution (too much for freshwater). The water would flow into their body until all their cells accumulate so much water that they bloat and die eventually.

Q25: If a DNA strand has a base sequence TCA, its complementary strand must be?
(a) ATG
(b) TAG
(c) GAT
(d) AGT
Ans: (d)
The complementary strand for TCA is AGT

• A    T
• G    C
• T    A
• C    G
• A    T
• T    A
• G    C
• A    T

Q26: The two key cations involved in the action potential of nervous transmissions are?
(a) Na⁺ and Fe²⁺
(b) Mg²⁺ and K⁺
(c) Na⁺ and K⁺
(d) Fe²⁺ and Mg²⁺
Ans: (c)
The Na⁺ / K⁺ - helps maintain resting potential, affects transport, and regulates cellular volume.

Q27: I. Rattus rattus. Il. Agama agama III. Bufo regularis IV. Tilapia  zillii
The order of evolutionary advancement of the above vertebrates is?
(a) I, II, III, IV
(b) I, IV, III, II
(c) II, III, IV, I
(d) IV, III, II, I
Ans: (d)
Evolutionary sequence in vertebrates: Fishes → Amphibians → Reptiles → Birds → Mammals.
IV → III → II → I

Q28: Which of the following produces both hormones and enzymes?
(a) Ileum
(b) Pancreas
(c) Gall bladder
(d) Kidney
Ans: (b)
The pancreas has two main functions: an exocrine function that helps in digestion and an endocrine function that regulates blood sugar.

Q29: The correct sequence of the movement of urea during urine formation is?
(a) glomerulus → Bowman's capsule → convoluted tubule→ Henle's loop → collecting- tubule
(b) glomerulus → Bowman's capsule → convoluted tubule → Henle's loop → convoluted tubule → collecting tubule
(c) convoluted tubule → glomerulus → Nettle's loop -> Bowman's capsule → collecting tubule
(d) convoluted tubule → Bowman's capsule → Henle's loop -7 → glomerulus → collecting tubule
Ans: (a)

• The kidneys filter unwanted substances from the blood and produce urine to excrete them.
• There are three main steps of urine formation: glomerular filtration, reabsorption, and tubular secretion.
• These processes ensure that only waste and excess water are removed from the body.

Q30: The order of passage of food in the digestive system is
(a) ileum → caecum → large intestine → rectum
(b) ileum → colon → caecum → rectum
(c) large intestine → ileum → caecum → rectum
(d) colon → caecum → ileum → rectum
Ans: (a)
The correct order of passage of food in the digestive system is option A: ileum → caecum → large → intestine → rectum.

Here's a breakdown of the order of passage of food through the digestive system:

• Ileum: The partially digested food from the stomach enters the small intestine, where most of the digestion and absorption of nutrients occur. The last part of the small intestine is called the ileum.
• Caecum: From the ileum, the undigested material passes into the caecum, which is the first part of the large intestine.
• Large intestine: The undigested material moves through the large intestine, which consists of the colon and the rectum. In the large intestine, water and electrolytes are absorbed from the remaining food, and the waste material becomes more solid.
• Rectum: The waste material, known as feces or stool, is stored in the rectum until it is ready to be eliminated from the body through the process of defecation.

Q31: Mass of a crucible = 10g,
Mass of a crucible and soil before heating =29g
Mass of a crucible and soil after heating = 18g
From the information above, determine the percentage of water in the given soil sample?
(a) 20%
(b) 25%
(c) 40%
(d) 60%
Ans: (d)

Q32: I. Stomata → Spirogyra
II. Alveoli → Earthworm
III. Malpighian tubule → Mammal
IV. Contractile vacuole → Protozoa
Q. Which of the above structures is correctly matched with the organisms in which it is found?
(a) II
(b) I
(c) IV
(d) III
Ans: (c)

• Stomata allow a plant to take in carbon dioxide, which is needed for photosynthesis. They also help to reduce water loss.
• The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.
• The Malpighian tubules are tubular structures that are free floating in the haemolymph and function as excretory and osmoregulatory organs of insects.
•  Contractile vacuoles (in the cells of the lower organisms) protect a cell from absorbing too much water and potentially exploding by excreting excess water.

Q33: The sequence of the one-way gaseous exchange mechanism in a fish is?
(a) mouth → operculum → gills
(b) mouth → gills > operculum
(c) operculum → gills → mouth
(d) gills → operculum → mouth
Ans: (b)
Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides(opercula) of the pharynx.

Q34: Which of the following is true in blood transfusion?
(a) A person of blood group AB can donate blood only to another person of blood group AB
(b) Persons of blood groups A and B can donate or receive blood from each other
(c) A person of blood group AB can receive blood only from persons of blood group A or B
(d) A person of blood group O can donate only to a person of blood group O
Ans: (a)

• People with type AB+ blood are universal recipients because they have no antibodies to A, B or Rh in their blood and can receive red blood cells from a donor of any blood type.
• Donors with blood type AB can donate to recipients with blood type AB only.

Q35: The plants that grow in deserts or very dry areas are referred to as?
(a) hydrophytes
(b) epiphytes
(c) xerophytes
(d) mesophytes
Ans: (c)

• Plants that live in water and adapt to their environment are known as hydrophytes.
• Epiphyte, also called air plant, any plant that grows upon another plant or object merely for physical support.
•  Plants that grow in dry habitat are called xerophytes.
• Mesophytes are terrestrial plants which are neither adapted to particularly dry nor particularly wet environments.

Q36: The most abundant group of organisms in the animal kingdom?
(a) Mammalia
(b) Aves
(c) Insecta
(d) Annelida
Ans: (c)
The phylum Arthropoda is the largest in the animal kingdom, having its class Insecta as 70% of all known species of animals.

Q37: The movement of part of a plant in response to external stimulus of no particular direction is?
(a) taxism
(b) tropism
(c) haptotropic movement
(d) nastic movement
Ans: (d)

• Taxism: oriented movement of a motile organism in response to an external stimulus, as toward or away from light.
• A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus.
•  In tropisms, this response is dependent on the direction of the stimulus.
• The movement or directional growth of plants or plant organs (as the tendrils of climbing plants) in response to the stimulus of touch.
• The non-directional movement (of plants) in response to a stimulus (e.g. humidity, temperature, light irradiance, nutrients, gravity, etc.

Q38: The mutation theory of organic evolution was propounded by?
(a) Gregor Mendel
(b) Hugo de Vries
(c) Jean Lamarck
(d) Charles Darwin
Ans: (b)

• Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance. 
• Hugo de Vries (1901) put forward a theory of evolution, called mutation theory. 
• Jean Baptiste Lamarck believed that traits changed or acquired over an individual's lifetime could be passed down to its offspring.
• The Theory of Evolution by natural selection was first formulated in Charles Darwin's book "On the Origin of Species" published in 1859.

Q39: If both parents are heterozygous for a trait. the probability that an offspring will be recessive for that trait is?
(a) 1/2
(b) 1/4
(c) 1
(d) 3/4
Ans: (a)

If both parents are heterozygous for a trait, it means they have one dominant allele and one recessive allele for that trait. In this case, the probability of each parent passing on the recessive allele to their offspring is 1/2.

Q40: Blood circulation in a mammal is said to be double because?
(a) it passes twice through the heart in a complete circuit
(b) it moves in both arteries and veins
(c) it circulates in both the heart and other organs
(d) the heart contains auricles and ventricles
Ans: (a)
It is called a double circulatory system because blood passes through the heart twice per circuit.