Question-1 Which polysaccharide is a major component of plant cell walls?
a) Glycogen
b) Starch
c) Cellulose
d) Chitin
Answer: c) Cellulose
Explanation:
Cellulose is a structural polysaccharide that provides rigidity to plant cell walls.
Question-2 Which lipid serves as a precursor for steroid hormones?
a) Phospholipid
b) Cholesterol
c) Triglyceride
d) Wax
Answer: b) Cholesterol
Explanation:
Cholesterol is the precursor for steroid hormones like estrogen and testosterone.
Question-3 Which bond holds the two strands of DNA together?
a) Covalent bond
b) Ionic bond
c) Hydrogen bond
d) Disulfide bond
Answer: c) Hydrogen bond
Explanation:
Hydrogen bonds between nitrogenous bases hold the two DNA strands together in a double helix.
Question-4 What is the end product of glycolysis?
a) Glucose
b) Pyruvate
c) ATP
d) Lactic acid
Answer: b) Pyruvate
Explanation:
Glycolysis breaks down glucose into two molecules of pyruvate, producing ATP and NADH.
Question-5 Which of the following is NOT an essential amino acid?
a) Valine
b) Leucine
c) Glycine
d) Methionine
Answer: c) Glycine
Explanation:
Essential amino acids must be obtained from the diet, while glycine can be synthesized by the body.
Question-6 What is the major excretory product in birds?
A) Ammonia
B) Urea
C) Uric acid
D) Creatinine
Answer: C) Uric acid
Explanation:
Birds are uricotelic, excreting nitrogenous waste as uric acid in solid or semi-solid form to conserve water.
Question-7 What is the function of the vasa recta in the nephron?
A) Produces urea
B) Helps in ultrafiltration
C) Maintains osmotic gradient
D) Controls urine pH
Answer: C) Maintains osmotic gradient
Explanation:
The vasa recta maintains the osmotic gradient in the renal medulla, aiding in water reabsorption and urine concentration.
Question-8 Why do desert animals produce highly concentrated urine?
A) To remove excess glucose
B) To prevent water loss
C) To store urea for later use
D) To remove excess oxygen
Answer: B) To prevent water loss
Explanation:
Desert animals have long Loops of Henle, which help in maximum water reabsorption and highly concentrated urine formation.
Question-9 Which condition is characterized by excessive urine output and thirst due to lack of ADH?
A) Diabetes mellitus
B) Gout
C) Diabetes insipidus
D) Kidney stones
Answer: C) Diabetes insipidus
Explanation:
Diabetes insipidus occurs due to ADH deficiency, leading to excessive urination and dehydration.
Question-10 Which of the following excretory organs is found in insects?
A) Nephridia
B) Malpighian tubules
C) Green glands
D) Kidneys
Answer: B) Malpighian tubules
Explanation:
Insects excrete nitrogenous waste through Malpighian tubules, which are involved in osmoregulation.
Question-11 What is the function of villi in the small intestine?
A) Produce digestive enzymes
B) Absorb nutrients
C) Store bile
D) Secrete insulin
Answer: B) Absorb nutrients
Explanation:
Villi increase the surface area of the small intestine, enhancing nutrient absorption into the blood.
Question-12 What is the final product of protein digestion?
A) Peptides
B) Amino acids
C) Fatty acids
D) Monosaccharides
Answer: B) Amino acids
Explanation:
Proteins are broken down into amino acids, which are absorbed by the small intestine.
Question-13 What causes jaundice?
A) Excess insulin
B) Increased bilirubin levels
C) Vitamin B12 deficiency
D) Low blood pressure
Answer: B) Increased bilirubin levels
Explanation:
Jaundice occurs due to excess bilirubin, often caused by liver dysfunction or bile duct obstruction.
Question-14 What is the function of the hormone secretin?
A) Stimulates gastric juice secretion
B) Enhances protein digestion
C) Stimulates bile and pancreatic juice secretion
D) Inhibits insulin release
Answer: C) Stimulates bile and pancreatic juice secretion
Explanation:
Secretin regulates pH balance by stimulating bile and pancreatic juice secretion to neutralize stomach acids.
Question-15 Which disease is caused by protein deficiency in children?
A) Rickets
B) Scurvy
C) Kwashiorkor
D) Diabetes
Answer: C) Kwashiorkor
Explanation:
Kwashiorkor is a protein-energy malnutrition disorder that causes swelling, muscle loss, and stunted growth in children.
Question-16 Which of the following best describes the amphibolic nature of the Krebs cycle?
A) It only breaks down glucose
B) It involves both catabolic and anabolic processes
C) It exclusively synthesizes biomolecules
D) It operates only during aerobic respiration
Answer: B) It involves both catabolic and anabolic processes
Explanation:
The Krebs cycle oxidizes Acetyl CoA for energy (catabolism) while also providing intermediates for biosynthesis (anabolism).
Question-17 What is the main advantage of stepwise oxidation in respiration?
A) Produces ATP in a single reaction
B) Releases energy gradually for controlled ATP synthesis
C) Prevents production of CO₂
D) Eliminates the need for enzymes
Answer: B) Releases energy gradually for controlled ATP synthesis
Explanation:
Stepwise oxidation allows efficient energy transfer and prevents heat damage to the cell.
Question-18 What is the role of ubiquinone (CoQ) in the electron transport chain?
A) Directly synthesizes ATP
B) Transfers electrons between Complex I and Complex III
C) Pumps protons across the inner membrane
D) Converts pyruvate into Acetyl CoA
Answer: B) Transfers electrons between Complex I and Complex III
Explanation:
CoQ (ubiquinone) is a mobile electron carrier between Complex I and Complex III.
Question-19 Which process occurs in both respiration and photosynthesis?
A) Glycolysis
B) Calvin cycle
C) Chemiosmosis
D) Alcoholic fermentation
Answer: C) Chemiosmosis
Explanation:
Both processes use a proton gradient to drive ATP synthesis via ATP synthase.
Question-20 Which factor can increase the rate of glycolysis?
A) High ATP concentration
B) High NADH concentration
C) High ADP concentration
D) Low glucose availability
Answer: C) High ADP concentration
Explanation:
Increased ADP signals low energy levels, promoting glycolysis for ATP production.
Question-21 What is the ploidy level of the zygote in angiosperms?
A) Haploid
B) Diploid
C) Triploid
D) Tetraploid
Answer: B) Diploid
Explanation:
The zygote is formed by the fusion of haploid male and female gametes, making it diploid.
Question-22 What is the role of cotyledons in seeds?
A) Absorb water
B) Protect the embryo
C) Provide nutrients to the developing embryo
D) Facilitate pollination
Answer: C) Provide nutrients to the developing embryo
Explanation:
Cotyledons store food and provide nutrients to the growing embryo until it can photosynthesize.
Question-23 Which of the following is an example of a parthenocarpic fruit?
A) Mango
B) Banana
C) Apple
D) Tomato
Answer: B) Banana
Explanation:
Parthenocarpy refers to the development of fruit without fertilization, as seen in seedless bananas.
Question-24 What is the function of aleurone layer in a seed?
A) Provides mechanical support
B) Protects the embryo
C) Aids in seed dormancy
D) Secretes enzymes to digest stored food during germination
Answer: D) Secretes enzymes to digest stored food during germination
Explanation:
The aleurone layer releases enzymes that break down stored food for seedling growth.
Question-25 In which type of pollination do pollen grains land on the stigma of a different flower of the same plant?
A) Autogamy
B) Geitonogamy
C) Xenogamy
D) Cleistogamy
Answer: B) Geitonogamy
Explanation:
In geitonogamy, pollen from one flower is transferred to another flower on the same plant.
Question-26 The first mitotic division of the zygote results in:
A) Blastocyst formation
B) Cleavage
C) Gastrulation
D) Implantation
Answer: B) Cleavage
Explanation:
The zygote undergoes cleavage, resulting in the formation of blastomeres.
Question-27 In which structure does implantation occur?
A) Ovary
B) Fallopian tube
C) Uterus
D) Cervix
Answer: C) Uterus
Explanation:
The fertilized egg implants in the uterus, where it develops into an embryo.
Question-28 What prevents polyspermy (entry of multiple sperms into an egg)?
A) Acrosomal reaction
B) Fertilization membrane formation
C) Capacitation
D) Follicular fluid
Answer: B) Fertilization membrane formation
Explanation:
The formation of a fertilization membrane prevents additional sperm from entering the egg.
Question-29 Which of the following is a birth control method that prevents sperm from reaching the egg?
A) Oral contraceptive pills
B) Copper-T (IUD)
C) Vasectomy
D) Condoms
Answer: D) Condoms
Explanation:
Condoms act as a barrier method to prevent sperm from reaching the egg.
Question-30 What is the term for pregnancy outside the uterus?
A) Ectopic pregnancy
B) Normal pregnancy
C) Superfetation
D) Parthenogenesis
Answer: A) Ectopic pregnancy
Explanation:
In an ectopic pregnancy, the fertilized egg implants outside the uterus, often in the fallopian tube.
Question-31 What is the name of the process where genes from different chromosomes assort independently into gametes?
A) Linkage
B) Independent Assortment
C) Crossing Over
D) Mutation
Answer: B) Independent Assortment
Explanation:
According to Mendel’s Law of Independent Assortment , alleles of different genes are inherited separately if they are on different chromosomes.
Question-32 Which of the following is an example of pleiotropy?
A) Blood groups
B) Skin color
C) Sickle cell anemia
D) Red and white flowers
Answer: C) Sickle cell anemia
Explanation:
In pleiotropy , one gene affects multiple traits. In sickle cell anemia , a mutation in the hemoglobin gene affects oxygen transport and blood cell shape.
Question-33 A person with blood group O has which genotype?
A) IAIA
B) IBIB
C) IAIB
D) ii
Answer: D) ii
Explanation:
Blood group O is determined by the recessive allele (i) , meaning the genotype must be ii .
Question-34 Which scientist first observed chromosomes?
A) Gregor Mendel
B) Waldeyer
C) Hugo de Vries
D) Thomas Hunt Morgan
Answer: B) Waldeyer
Explanation:
W. Waldeyer first observed and coined the term chromosome in 1888 .
Question-35 What is the function of the SRY gene in humans?
A) Determines female characteristics
B) Controls skin pigmentation
C) Determines male characteristics
D) Responsible for hemophilia
Answer: C) Determines male characteristics
Explanation:
The SRY (Sex-determining Region Y) gene on the Y chromosome triggers male development.
Question=36 Which molecule acts as an inducer in the lac operon?
A) Glucose
B) Lactose
C) Repressor
D) ATP
Answer: B) Lactose
Explanation:
Lactose binds to the repressor , removing it from the operator, allowing transcription of lac genes.
Question-37 In prokaryotes, where does translation occur?
A) Nucleus
B) Cytoplasm
C) Mitochondria
D) Golgi apparatus
Answer: B) Cytoplasm
Explanation:
Prokaryotic translation occurs in the cytoplasm immediately after transcription.
Question-38 What type of bond holds the two DNA strands together?
A) Phosphodiester bond
B) Hydrogen bond
C) Glycosidic bond
D) Peptide bond
Answer: B) Hydrogen bond
Explanation:
Hydrogen bonds between complementary base pairs hold the two DNA strands together.
Question-39 What is a polycistronic mRNA?
A) mRNA that codes for multiple proteins
B) mRNA with multiple introns
C) mRNA with a poly-A tail
D) mRNA that undergoes alternative splicing
Answer: A) mRNA that codes for multiple proteins
Explanation:
Prokaryotic mRNAs are often polycistronic , meaning they encode multiple proteins.
Question-40 What is a codon?
A) Three consecutive nucleotides in mRNA
B) A gene segment
C) A ribosomal protein
D) An amino acid
Answer: A) Three consecutive nucleotides in mRNA
Explanation:
A codon is a triplet sequence of nucleotides that codes for an amino acid.
Question-41 What does the fossil record provide evidence for?
A) Genetic drift
B) Gradual changes in species over time
C) Hardy-Weinberg equilibrium
D) Spontaneous generation
Answer: B) Gradual changes in species over time
Explanation:
Fossils show progressive changes in organisms , supporting evolution.
Question-42 Which dating method is used to determine the age of fossils?
A) Spectroscopy
B) Carbon dating
C) Electrophoresis
D) PCR
Answer: B) Carbon dating
Explanation:
Carbon-14 dating measures the decay of radioactive isotopes to estimate fossil age.
Question-43 Which of the following is NOT an evolutionary force?
A) Mutation
B) Genetic drift
C) Random mating
D) Natural selection
Answer: C) Random mating
Explanation:
Random mating maintains genetic equilibrium, whereas mutation, genetic drift, and natural selection drive evolution.
Question-44 What is the correct order of human evolution?
A) Australopithecus → Homo habilis → Homo erectus → Homo sapiens
B) Homo erectus → Australopithecus → Homo habilis → Homo sapiens
C) Homo habilis → Australopithecus → Homo sapiens → Homo erectus
D) Homo sapiens → Homo habilis → Australopithecus → Homo erectus
Answer: A) Australopithecus → Homo habilis → Homo erectus → Homo sapiens
Explanation:
This is the correct evolutionary sequence leading to modern humans.
Question-45 What is the significance of Homo habilis in human evolution?
A) First species to walk upright
B) First species to make tools
C) First species to migrate out of Africa
D) First species to use fire
Answer: B) First species to make tools
Explanation:
Homo habilis is known as “Handy Man” because they were the first to make simple tools.
Question-46 Which factor does NOT influence transpiration?
A) Light
B) Temperature
C) Root pressure
D) Wind
Answer: C) Root pressure
Explanation:
Root pressure contributes to water movement but does not directly influence transpiration .
Question-47 The movement of water through the symplast pathway occurs via:
A) Cell walls
B) Xylem
C) Plasmodesmata
D) Cuticle
Answer: C) Plasmodesmata
Explanation:
Symplast transport occurs through plasmodesmata , connecting cytoplasm of adjacent cells.
Question-48 Which type of transpiration occurs through stomata?
A) Cuticular transpiration
B) Stomatal transpiration
C) Lenticular transpiration
D) Hydathodal transpiration
Answer: B) Stomatal transpiration
Explanation:
Stomatal transpiration accounts for 90% of total water loss in plants.
Question-49 Which organelle in guard cells controls stomatal opening?
A) Mitochondria
B) Chloroplast
C) Nucleus
D) Vacuole
Answer: B) Chloroplast
Explanation:
Guard cell chloroplasts help detect light and regulate stomatal opening.
Question-50 What is the purpose of anti-transpirants?
A) Increase transpiration
B) Prevent stomatal closure
C) Reduce transpiration
D) Enhance guttation
Answer: C) Reduce transpiration
Explanation:
Anti-transpirants like silicone emulsions reduce water loss.
Question-51 The deficiency of which element causes “die-back” disease in citrus plants?
A) Copper
B) Boron
C) Phosphorus
D) Potassium
Answer: B) Boron
Explanation:
Boron deficiency leads to die-back disease , where terminal shoots die due to poor sugar transport .
Question-52 What is hydroponics?
A) Soil-based farming
B) Growing plants in nutrient-rich water
C) Growing plants without water
D) Mineral cycling in soil
Answer: B) Growing plants in nutrient-rich water
Explanation:
Hydroponics is a technique of growing plants without soil using nutrient solutions .
Question-53 Which nitrogen-fixing bacteria is found in the root nodules of legumes?
A) Azotobacter
B) Nitrosomonas
C) Rhizobium
D) Pseudomonas
Answer: C) Rhizobium
Explanation:
Rhizobium forms a symbiotic relationship with legume roots and fixes atmospheric nitrogen .
Question-54 Which process converts atmospheric nitrogen into ammonia?
A) Nitrification
B) Denitrification
C) Nitrogen fixation
D) Ammonification
Answer: C) Nitrogen fixation
Explanation:
Nitrogen fixation (by Rhizobium, Azotobacter, etc.) converts N₂ into NH₃ .
Question-55 Which plant hormone delays leaf senescence?
A) Auxin
B) Cytokinin
C) Gibberellin
D) Ethylene
Answer: B) Cytokinin
Explanation:
Cytokinins delay leaf senescence (anti-aging hormone) by promoting nutrient mobilization.
Question-56 What happens during systole?
A) The heart relaxes
B) The heart contracts and pumps blood
C) Blood fills the ventricles
D) Blood flows into the veins
Answer: B) The heart contracts and pumps blood
Explanation:
Systole is the contraction phase , pumping blood into arteries .
Question-57 Which chamber of the heart has the thickest walls?
A) Right atrium
B) Right ventricle
C) Left atrium
D) Left ventricle
Answer: D) Left ventricle
Explanation:
The left ventricle has thicker muscular walls to pump oxygenated blood to the entire body .
Question-58 What is stroke volume?
A) Volume of blood pumped by the heart per minute
B) Volume of blood pumped per beat
C) Volume of blood remaining in the heart
D) Total blood volume in the body
Answer: B) Volume of blood pumped per beat
Explanation:
Stroke volume is the amount of blood ejected per heartbeat (~70 mL in an adult).
Question-59 What causes the “lub-dub” sound of the heartbeat?
A) Contraction of heart muscles
B) Movement of blood through arteries
C) Closing of heart valves
D) Opening of heart valves
Answer: C) Closing of heart valves
Explanation:
The “lub” sound is due to AV valve closure , and the “dub” sound is due to semilunar valve closure .
Question-60 Which respiratory pigment is found in vertebrates?
A) Hemocyanin
B) Chlorocruorin
C) Hemoglobin
D) Hemerythrin
Answer: C) Hemoglobin
Explanation: Hemoglobin is the iron-containing respiratory pigment in vertebrates that transports oxygen.
Question-61 What is the role of oxytocin?
A) Induces labor contractions
B) Controls metabolism
C) Increases blood sugar
D) Regulates water balance
Answer: A) Induces labor contractions
Explanation:
Oxytocin stimulates uterine contractions during childbirth and milk ejection during lactation.
Question-62 Which gland produces melatonin, the sleep-regulating hormone?
A) Pituitary gland
B) Pineal gland
C) Adrenal gland
D) Thyroid gland
Answer: B) Pineal gland
Explanation:
The pineal gland secretes melatonin , which regulates the sleep-wake cycle (circadian rhythm).
Question-63 Which of the following is an example of a conditioned reflex?
A) Blinking of the eye
B) Withdrawal of hand from heat
C) Salivation at the sight of food
D) Knee-jerk reflex
Answer: C) Salivation at the sight of food
Explanation:
Conditioned reflexes are learned responses, such as Pavlov’s experiment with dogs salivating at a bell sound .
Question-64 What is the function of the hypothalamus?
A) Controls voluntary movements
B) Regulates hunger, thirst, and temperature
C) Produces cerebrospinal fluid
D) Coordinates reflexes
Answer: B) Regulates hunger, thirst, and temperature
Explanation:
The hypothalamus regulates body temperature, hunger, thirst, and hormone secretion .
Question-65 Which part of the brain controls balance and coordination?
A) Cerebrum
B) Cerebellum
C) Medulla oblongata
D) Hypothalamus
Answer: B) Cerebellum
Explanation:
The cerebellum coordinates voluntary movements and maintains balance and posture .
Question-66 The drug used for the treatment of malaria is:
A) Penicillin
B) Streptomycin
C) Quinine
D) Morphine
Answer: C) Quinine
Explanation:
Quinine and Chloroquine are commonly used anti-malarial drugs .
Question-67 What is metastasis?
A) Uncontrolled cell division
B) Spread of cancer cells to other body parts
C) Growth of tumors in one location
D) Inflammation of lymph nodes
Answer: B) Spread of cancer cells to other body parts
Explanation:
Metastasis is the spread of cancer from the primary site to distant organs .
Question-68 Which type of tumor is cancerous and spreads to other tissues?
A) Benign tumor
B) Malignant tumor
C) Lipoma
D) Fibroma
Answer: B) Malignant tumor
Explanation:
Malignant tumors grow rapidly and invade nearby tissues , spreading through blood and lymph .
Question-69 The Ames test is used to detect:
A) Blood sugar levels
B) Cancer-causing agents
C) Antibody production
D) Vitamin deficiencies
Answer: B) Cancer-causing agents
Explanation:
The Ames test is a genetic mutation test used to detect potential carcinogens .
Question-70 The term “Golden Hour” in medical emergencies refers to:
A) The first 60 minutes after a heart attack or stroke
B) The recovery phase of a patient
C) The best time for vaccination
D) The duration of drug action
Answer: A) The first 60 minutes after a heart attack or stroke
Explanation:
The Golden Hour is critical for saving lives , especially after heart attacks, strokes, and major injuries .
Question-71 Which microorganism is used in the fermentation of curd?
A) Saccharomyces
B) Lactobacillus
C) Aspergillus
D) Rhizopus
Answer: B) Lactobacillus
Explanation:
Lactobacillus bacteria convert milk into curd through lactic acid fermentation .
Question-72 What is the purpose of hydroponics in agriculture?
A) Reduce fertilizer use
B) Grow plants without soil
C) Increase microbial activity
D) Improve pollination
Answer: B) Grow plants without soil
Explanation:
Hydroponics is a technique of growing plants in nutrient-rich water without soil .
Question-73 Which of the following is an example of biofertilizer?
A) Urea
B) Ammonium nitrate
C) Rhizobium
D) Superphosphate
Answer: C) Rhizobium
Explanation:
Rhizobium is a nitrogen-fixing bacterium that enhances soil fertility.
Question-74 Which technique is used for breeding animals with superior traits?
A) Inbreeding
B) Outbreeding
C) Hybridization
D) Artificial insemination
Answer: D) Artificial insemination
Explanation:
Artificial insemination is a technique for introducing superior-quality semen into female animals for selective breeding.
Question-75 Which of the following is a high-yielding variety of sugarcane?
A) Co-419
B) IR-36
C) Kalyan Sona
D) Sonalika
Answer: A) Co-419
Explanation:
Co-419 is a high-yielding sugarcane variety developed for better production.
Question-76 The first genetically modified animal was:
A) Glowfish
B) Dolly the sheep
C) Supermouse
D) Goat
Answer: C) Supermouse
Explanation:
Supermouse was the first transgenic animal , genetically engineered for growth hormone expression .
Question-77 Which type of RNA is used in RNA interference (RNAi)?
A) mRNA
B) tRNA
C) siRNA
D) rRNA
Answer: C) siRNA
Explanation:
Small interfering RNA (siRNA) is used in RNA interference (RNAi) to silence specific genes .
Question-78 Gene therapy is used to treat:
A) Viral infections
B) Genetic disorders
C) Bacterial diseases
D) Nutritional deficiencies
Answer: B) Genetic disorders
Explanation:
Gene therapy is used to replace or repair defective genes in patients with genetic disorders.
Question-79 The first gene therapy was performed to treat:
A) Cystic fibrosis
B) Severe Combined Immunodeficiency (SCID)
C) Cancer
D) Sickle cell anemia
Answer: B) Severe Combined Immunodeficiency (SCID)
Explanation:
Gene therapy was first used in 1990 to treat a SCID patient by introducing a functional ADA gene.
Question-80 What is the role of bioinformatics in biotechnology?
A) Studying ecological systems
B) Analyzing genetic and protein data
C) Cultivating genetically modified crops
D) Producing vaccines
Answer: B) Analyzing genetic and protein data
Explanation:
Bioinformatics uses computational tools to analyze DNA, RNA, and protein sequences .
Question-81 Which interaction is beneficial for both species involved?
A) Commensalism
B) Amensalism
C) Mutualism
D) Parasitism
Answer: C) Mutualism
Explanation:
Mutualism is a symbiotic relationship where both species benefit , like bees pollinating flowers .
Question-82 Which survivorship curve is typical for humans?
A) Type I (convex)
B) Type II (constant mortality)
C) Type III (concave)
D) Exponential curve
Answer: A) Type I (convex)
Explanation:
Humans exhibit a Type I survivorship curve , with low mortality at a young age and high survival rates into adulthood .
Question-83 What does the age pyramid of a rapidly growing population look like?
A) Narrow at the base and wider at the top
B) Uniform throughout
C) Broad at the base and narrow at the top
D) Inverted pyramid
Answer: C) Broad at the base and narrow at the top
Explanation:
A broad base indicates a high birth rate and rapid population growth .
Question-84 Which adaptation allows desert animals to conserve water?
A) Producing highly dilute urine
B) Behavioral cooling (burrowing)
C) Increased sweating
D) Large body size
Answer: B) Behavioral cooling (burrowing)
Explanation:
Desert animals reduce water loss by staying underground during the hottest parts of the day.
Question-85 Which factor regulates population growth through competition and predation?
A) Density-independent factors
B) Abiotic factors
C) Density-dependent factors
D) Random mutations
Answer: C) Density-dependent factors
Explanation:
Density-dependent factors like competition, predation, and disease increase in intensity as population density rises.
Question-86 Which of the following best describes a food web?
A) A simple linear sequence of energy flow
B) Interconnected food chains
C) A pyramid of energy transfer
D) A representation of biomass flow
Answer: B) Interconnected food chains
Explanation:
Food webs are complex networks of interconnected food chains in an ecosystem.
Question-87 Which pyramid can be inverted in an aquatic ecosystem?
A) Pyramid of energy
B) Pyramid of biomass
C) Pyramid of numbers
D) Pyramid of productivity
Answer: B) Pyramid of biomass
Explanation:
In aquatic ecosystems , phytoplankton (producers) have lower biomass than consumers, forming an inverted biomass pyramid .
Question-88 Secondary consumers in an ecosystem feed on:
A) Producers
B) Herbivores
C) Carnivores
D) Decomposers
Answer: B) Herbivores
Explanation:
Secondary consumers (carnivores) feed on herbivores (primary consumers) .
Question-89 The term “standing crop” refers to:
A) The total biomass of organisms in a trophic level
B) The rate of energy production
C) The total number of individuals in an ecosystem
D) The mineral content of soil
Answer: A) The total biomass of organisms in a trophic level
Explanation:
Standing crop is the total living biomass at a given time.
Question-90 Which nutrient cycle does not have a significant atmospheric component?
A) Carbon cycle
B) Nitrogen cycle
C) Phosphorus cycle
D) Oxygen cycle
Answer: C) Phosphorus cycle
Explanation:
The phosphorus cycle occurs mainly in soil, rocks, and water , with minimal atmospheric involvement .
Question-91 What is the major cause of ozone depletion?
A) Carbon monoxide
B) Chlorofluorocarbons (CFCs)
C) Oxygen
D) Nitrogen oxides
Answer: B) Chlorofluorocarbons (CFCs)
Explanation:
CFCs break down ozone molecules, creating the ozone hole over Antarctica.
Question-92 Which of the following is an example of solid waste pollution?
A) Noise from industries
B) Oil spills in oceans
C) Plastic accumulation in landfills
D) Carbon dioxide emissions
Answer: C) Plastic accumulation in landfills
Explanation:
Solid waste pollution includes non-biodegradable waste like plastic that accumulates in landfills.
Question-93 Which of the following methods can reduce water pollution?
A) Burning fossil fuels
B) Dumping waste into rivers
C) Wastewater treatment
D) Deforestation
Answer: C) Wastewater treatment
Explanation:
Wastewater treatment plants remove pollutants from water before it is released into the environment.
Question-94 What is biomagnification?
A) Increase in population
B) Increase in pollutant concentration along the food chain
C) Increase in forest cover
D) Increase in genetic variation
Answer: B) Increase in pollutant concentration along the food chain
Explanation:
Biomagnification causes toxins (e.g., DDT, mercury) to accumulate in higher trophic levels .
Question-95 The process of forest degradation due to human activities is called:
A) Desertification
B) Deforestation
C) Biodiversity loss
D) Ozone depletion
Answer: B) Deforestation
Explanation:
Deforestation is the permanent removal of forests , affecting climate and biodiversity.
Question-96 What happens to NADH produced in glycolysis under anaerobic conditions?
A) It is used in the electron transport chain
B) It donates electrons to pyruvate, forming lactic acid
C) It gets stored in the cell for later use
D) It directly produces ATP
Answer: B) It donates electrons to pyruvate, forming lactic acid
Explanation:
In anaerobic conditions, NADH is oxidized by transferring electrons to pyruvate, regenerating NAD⁺ for glycolysis.
Question-97 Which type of sex determination system is found in birds?
A) XX-XY
B) XO-XX
C) ZW-ZZ
D) Haplo-diploidy
Answer: C) ZW-ZZ
Explanation:
In birds, females have ZW sex chromosomes, while males have ZZ .
Question-98 Water enters guard cells due to:
A) Active transport
B) Increase in osmotic pressure
C) Loss of turgor pressure
D) ATP hydrolysis
Answer: B) Increase in osmotic pressure
Explanation:
When guard cells absorb K⁺ ions , water follows by osmosis , making them turgid.
Question-99 Which blood vessel carries oxygenated blood from the heart to the body?
A) Pulmonary artery
B) Pulmonary vein
C) Vena cava
D) Aorta
Answer: D) Aorta
Explanation:
The aorta is the largest artery and carries oxygenated blood from the left ventricle to the body.
Question-100 What is anaphylaxis?
A) Mild allergic reaction
B) Autoimmune disorder
C) Life-threatening allergic reaction
D) Chronic infection
Answer: C) Life-threatening allergic reaction
Explanation:
Anaphylaxis is a severe, rapid allergic reaction that can cause shock, swelling, and difficulty breathing .