Explanation: The scientific classification of humans is Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Order: Primates, Family: Hominidae, Genus: Homo, Species: sapiens. Thus, the genus is Homo.
Q2.Which of the following is a characteristic feature of insects?
A.Presence of feathers
Jointed appendages
C.Gills for respiration
D.Internal fertilization
Explanation: Insects belong to the phylum Arthropoda and are characterized by jointed appendages, including legs and antennae, which allow for mobility and various functions.
Q3.The growth process that involves shedding of the exoskeleton in arthropods is
A.metamorphosis
ecdysis
C.hibernation
D.aestivation
Explanation: Ecdysis is the process where arthropods, like insects, shed their old exoskeleton to allow for growth, as the rigid exoskeleton does not expand.
Q4.In a dicotyledonous leaf, the midrib is primarily responsible for
A.photosynthesis
support and transport
C.reproduction
D.storage
Explanation: The midrib in a dicot leaf contains vascular tissues (xylem and phloem) that provide structural support and transport water, nutrients, and sugars.
Q5.The vascular bundle in a dicot leaf consists of
A.phloem only
B.xylem only
both xylem and phloem
D.epidermis only
Explanation: In dicot leaves, vascular bundles are collateral, containing both xylem (for water transport) and phloem (for food transport), arranged in a network.
Q6.The functions of vacuoles in plants are storage and
A.protection
B.strength
support
D.sensitivity
Explanation: Plant vacuoles store water, ions, and nutrients, and maintain turgor pressure, which provides mechanical support to the cell and plant structure.
Q7.A plant cell placed in a concentrated salt solution will undergo
A.turgidity
plasmolysis
C.cytolysis
D.diffusion
Explanation: In a hypertonic solution like concentrated salt, water moves out of the plant cell by osmosis, causing the cytoplasm to shrink away from the cell wall, known as plasmolysis.
Q8.The shrinkage of the cytoplasm away from the cell wall in plant cells is known as
A.haemolysis
B.crenation
C.turgor
plasmolysis
Explanation: Plasmolysis occurs when plant cells lose water in a hypertonic environment, causing the plasma membrane to pull away from the cell wall.
Q9.How many molecules of oxygen are required for the aerobic respiration of three molecules of glucose?
A.3
B.6
C.12
18
Explanation: The equation for aerobic respiration of one glucose is C6H12O6 + 6O2 → 6CO2 + 6H2O + energy. For three glucose molecules, 3 × 6 = 18 O2 molecules are required.
Q10.Sclerenchyma tissue in plants is for
A.water conduction
mechanical support
C.food storage
D.food transport
Explanation: Sclerenchyma cells have thick, lignified walls that provide rigid mechanical support to plant parts like stems and veins.
Q11.The process by which a white blood cell engulfs a pathogen is
A.pinocytosis
phagocytosis
C.osmosis
D.diffusion
Explanation: Phagocytosis is the process where phagocytes, like white blood cells, engulf and destroy pathogens through endocytosis.
Q12.The cells responsible for defence against pathogens in human blood are
A.erythrocytes
leucocytes
C.thrombocytes
D.plasma cells
Explanation: Leucocytes (white blood cells) are part of the immune system and defend against pathogens through phagocytosis and antibody production.
Q13.Which of the following statements is not correct about respiration in plants?
A.It occurs in all plant tissues
Light and chlorophyll must be present for it to occur
C.Energy is produced as the end product
D.It occurs in the presence of oxygen
Explanation: Respiration in plants is a continuous process that does not require light or chlorophyll; it occurs in mitochondria using oxygen to release energy from glucose.
Q14.Urine, when compared with blood in mammals is hypertonic because
A.urine contains high percentage of all cells
B.all traces of sugar have been removed from urine
C.urea is actively secreted into the renal tubules
much water has been removed from urine
Explanation: In the loop of Henle and collecting ducts, water is reabsorbed from the filtrate, concentrating the urine to make it hypertonic compared to blood.
Q15.The naturally produced auxin in plants is
indole acetic acid
B.dichlorophenoxyacetic acid
C.aldone
D.florigen
Explanation: Indole-3-acetic acid (IAA) is the primary natural auxin produced by plants, promoting cell elongation and apical dominance.
Q16.The sympathetic nervous system causes
constriction of the arteries
B.heartbeat to slow down
C.increase in the secretion of saliva
D.contraction of the bladder
Explanation: The sympathetic nervous system activates the 'fight or flight' response, causing vasoconstriction in arteries to redirect blood to vital organs.
Q17.Long sightedness could be corrected using
A.biconvex lens
convex lens
C.biconcave lens
D.concave lens
Explanation: Hypermetropia (long-sightedness) is corrected with a convex lens, which converges light rays to focus on the retina.
Q18.During the process of hearing in mammals, the structure in the middle ear which receives the first vibration is the
A.oval window
B.round window
C.incus
malleus
Explanation: The malleus (hammer), the outermost ossicle, attaches to the eardrum and receives initial vibrations from sound waves.
Q19.An important characteristic of fruits dispersed by water is the presence of
fibrous covering
B.smooth surface
C.water content
D.pericarp
Explanation: Fruits like coconuts have fibrous, buoyant husks that aid flotation and dispersal by water currents.
Q20.Plants which grow and produce fruits within a year are called
A.biennials
B.perennials
annuals
D.herbs
Explanation: Annual plants complete their life cycle, including growth, reproduction, and death, within one year.
Q21.Chemical digestion in organisms is the
A.breakdown of starch into carbohydrates
breakdown of complex molecules into simple molecules
C.build up of simple insoluble molecules into complex
D.build up of soluble molecules into complex insoluble molecules
Explanation: Chemical digestion uses enzymes to hydrolyze large, complex molecules (e.g., proteins, starches) into smaller, absorbable simple molecules.
Q22.Excessive bleeding from an injury could be due to the lack of vitamin
K
B.E
C.B
D.A
Explanation: Vitamin K is essential for blood clotting; deficiency leads to prolonged bleeding due to impaired coagulation factor synthesis.
Q23.Enzymatic digestion of protein begins in the
A.mouth
stomach
C.small intestine
D.large intestine
Explanation: Protein digestion starts in the stomach with pepsin, an enzyme activated in the acidic environment, breaking proteins into peptides.
Q24.The parts of the digestive system that secrete substances involved in the digestion of fats are
A.mouth and stomach
B.stomach and pancreas
pancreas and small intestine
D.small and large intestine
Explanation: The pancreas secretes lipase for fat emulsification, and the small intestine receives bile from the liver/gallbladder to break down fats.
Q25.If the small intestine of an organism does not have villi, the organism will have a problem with
A.digestion of food only
B.absorption of water
absorption of nutrients only
D.digestion of food and absorption of nutrients
Explanation: Villi increase surface area for nutrient absorption in the small intestine; without them, digested nutrients cannot be efficiently absorbed.
Q26.Which of the following statements is not correct about the dental formula of humans?
One pair of canines is on the upper jaw and three pairs of premolars are on the lower jaw
B.Two pairs of incisors are on the upper jaw and three pairs of premolars are on the lower jaw
C.Two pairs of incisors are on the upper jaw and three pairs of molars are on the lower jaw
D.One pair of canines is on the upper jaw and four pairs of molars are on the lower jaw
Explanation: Human dental formula is I 2/2, C 1/1, PM 2/2, M 3/3. Canines are 1/1 (one pair each jaw), premolars 2/2 (two pairs each), so A is incorrect.
Q27.The relationship between a bean plant and a Tithonia plant on a farmland is
Competition
B.predation
C.Parasitism
D.epiphytism
Explanation: Both bean and Tithonia (Mexican sunflower) are plants competing for the same resources like sunlight, water, and nutrients in the soil.
Q28.The following ecological factors affect all habitats except
A.temperature
B.Humidity
C.light
pressure
Explanation: Pressure is a significant factor only in aquatic or high-altitude habitats, not all ecosystems like terrestrial ones.
Q29.An instrument commonly used to measure underwater visibility in aquatic ecosystems is
A.wind vane
B.thermometer
Secchi disc
D.barometer
Explanation: The Secchi disc is lowered into water until invisible, measuring turbidity and light penetration to assess visibility.
Q30.The Secchi disc is primarily used to measure
A.wind speed
B.temperature
water transparency
D.humidity
Explanation: It quantifies water clarity by determining the depth at which the disc becomes obscured by suspended particles.
Q31.When Tilapia population in a pond reaches the carrying capacity, the population
A.alternately increases and decreases
remains unchanged
C.increases only
D.decreases only
Explanation: Carrying capacity is the maximum population size an environment can sustain; at this point, birth and death rates balance, stabilizing the population.
Q32.Which of the following statements about the pyramid of energy is correct?
A.Energy remains constant across trophic levels
Energy decreases from the base to the apex of the pyramid
C.Energy increases from the base to the apex of the pyramid
D.Each trophic level is an independent energy source
Explanation: Only about 10% of energy transfers to the next trophic level due to heat loss and incomplete consumption, so energy decreases upward.
Q33.Which of the following sequences represents the trend in eutrophication?
A.Heavy mineralization → lack of oxygen → massive algal growth
Excessive nitrates → massive algal growth → lack of oxygen → death of aquatic organisms
C.Excessive phosphates → lack of oxygen → massive algal growth → death of aquatic organisms
D.Massive algal growth → excessive nitrates → lack of oxygen
Explanation: Eutrophication begins with nutrient enrichment (nitrates/phosphates), leading to algal blooms, oxygen depletion upon decay, and organism death.
Q34.Which of the following statements correctly describes the term population? The number of
Tilapia in a lake
B.fungus and snail on leaf litter
C.bees and butterflies on a flower
D.flatworms and roundworms in the gut of an animal
Explanation: A population is a group of individuals of the same species in a specific area; Tilapia (same species) in a lake fits this definition.
Q35.What is the population density of Ageratum sp. of frequency 1,850 on a land area measuring 100m²?
18.50/m²
B.8.05/m²
C.0.50/m²
D.0.05/m²
Explanation: Population density = total number (frequency) / area = 1850 / 100 m² = 18.5 individuals per m².
Q36.Which of the following activities does not control pathogens?
A.Exposure to ultraviolet radiation
B.Use of disinfectants
Eating balanced diet
D.Boiling water
Explanation: A balanced diet supports immunity but does not directly control or kill pathogens; the others are direct antimicrobial methods.
Q37.Which of the following could be prevented by a BCG vaccination?
A.Malaria
B.Cholera
Tuberculosis
D.Diphtheria
Explanation: BCG vaccine provides immunity against Mycobacterium tuberculosis, preventing severe forms of tuberculosis, especially in children.
Q38.The main effect of deforestation is
A.creation of new habitats
loss of soil particles
C.survival of more species
D.reduction of carbon (IV) oxide in the atmosphere
Explanation: Deforestation removes tree roots that bind soil, leading to increased erosion and loss of topsoil particles.
Q39.Which of the following resources cannot be conserved?
A.Mineral resources
B.Soil and water
C.Forests and wildlife
Domestic wastes
Explanation: Domestic wastes are byproducts that require management and disposal, not conservation as renewable resources; the others can be conserved through sustainable practices.
Q40.Which of the following activities is not suitable for forest conservation?
Felling of trees
B.Planting seedlings
C.Preventing bush fires
D.Planting tree crops
Explanation: Felling trees reduces forest cover and biodiversity; conservation involves sustainable practices like replanting and fire prevention.