This includes questions from Class 12 Biology chapters.
Q 1: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (4) A-IV, B-III, C-II, D-I
▶️ Microsporogenesis: Formation of microspores from pollen mother cell through meiosis. As the anthers mature and dehydrate, the microspores dissociate each other and develop into pollen grains.
▶️ Megasporogenesis: Formation of megaspores from megaspore mother cell (MMC). Ovules generally differentiate a single MMC in micropylar region of the nucellus.
▶️ Portion of embryonal axis above the level of cotyledons is the epicotyl, which terminates with plumule (stem tip).
▶️ The cylindrical portion below the level of cotyledons is hypocotyl that terminates with the radicle (root tip).
Q 2: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (2) A-II, B-III, C-IV, D-I
▶️ Sperm head is formed of nucleus and acrosome. Acrosome is formed from Golgi complex. It contains enzymes that help fertilisation of ovum.
▶️ Secondary oocyte is surrounded by a new membrane called zona pellucida.
▶️ A blastocyst has an outer layer called trophoblast and an inner cell mass. The trophoblast gives nourishment to inner cell mass. Inner cell mass becomes embryo.
▶️ Placenta secretes Human chorionic gonadotropin (hCG), human placental lactogen (hPL), oestrogens, progesterone & relaxin.
Q 3: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (3) A-III, B-I, C-IV, D-II
Phases of Menstrual cycle
▶️ 1. Menstrual phase: Shedding of the uterine lining, marked by menstrual bleeding.
▶️ 2. Follicular phase: Development of ovarian follicles.
▶️ 3. Ovulatory phase: Release of the mature egg (ovulation) from the ovary into the fallopian tube.
▶️ 4. Luteal phase: The ruptured follicle transforms into the corpus luteum, which produces progesterone. If fertilization doesn't occur, the corpus luteum degenerates, leading to a new menstrual cycle.
Q 4: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (1) A-II, B-I, C-IV, D-III
Changes in embryo during pregnancy
▶️ After one month: Heart is formed.
▶️ End of second month: Limbs and digits are developed.
▶️ End of 12 weeks (first trimester): Major organs (limbs, external genital organs etc.) are well developed.
▶️ During 5th month: First movement of foetus and appearance of hair on the head.
▶️ End of 24 weeks (end of 2nd trimester): Body is covered with fine hair; eyelids separate and eye lashes form.
▶️ End of 9 months: Ready for delivery.
Q 5: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (1) A-IV, B-I, C-II, D-III
▶️ Zygote Intra Fallopian Transfer (ZIFT): Transfer of zygote or early embryo (with up to 8 blastomeres) into fallopian tube.
▶️ Intra Uterine Transfer (IUT): Transfer of embryo with more than 8 blastomeres into the uterus.
▶️ Gamete Intra Fallopian Transfer (GIFT): Transfer of an ovum from a donor into the fallopian tube of another female who cannot produce ovum, but can provide suitable environment for fertilization & development.
▶️ Intra cytoplasmic sperm injection (ICSI): In this, a sperm is injected directly into an egg. After fertilization, the embryo is implanted into the uterus. It is useful for very low sperm count problem.
Q 6: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (4) A-IV, B-III, C-II, D-I
▶️ In 1900, de Vries, Correns & von Tschermak independently rediscovered Mendel’s results.
▶️ Chromosomal Theory of Inheritance was proposed by Walter Sutton & Theodore Boveri. They said that pairing & separation of a chromosome pair lead to segregation of a pair of factors they carry.
▶️ Alfred Sturtevant used the recombination frequency between gene pairs for measuring the distance between genes and mapped their position on the chromosome.
▶️ Henking studied spermatogenesis in some insects and discovered X body (X-chromosome).
Q 7: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (2) A-III, B-IV, C-I, D-II
Mechanisms of sex determination
▶️ a. XX-XO mechanism: Here, male is heterogametic, i.e. XO (Gametes with X and gametes without X) and female is homogametic, i.e. XX (all gametes are with X-chromosomes). E.g. Many insects such as grasshopper.
▶️ b. XX-XY mechanism: Male is heterogametic (X & Y) and female is homogametic (X only). E.g. Human & Drosophila.
▶️ c. ZZ-ZW mechanism: Male is homogametic (ZZ) and female is heterogametic (Z & W). E.g. Birds.
▶️ Haplodiploid sex determination system: Seen in insects such as honeybees. The females are diploid (32 chromosomes) and males are haploid (16 chromosomes). Males produce sperms by mitosis.
Q 8: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-IV, B-III, C-II, D-I
✅ (3) A-III, B-I, C-IV, D-II
▶️ Secondary (2-D) structure of tRNA looks like a clover-leaf. 3-D structure looks like inverted ‘L’.
▶️ Lac operon is an operon that controls lactose metabolism in bacteria. It was first elucidated by Francois Jacob & Jacque Monod.
▶️ Average gene consists of 3000 bases, but sizes vary. Largest known human gene (dystrophin on X-chromosome) contains 2.4 million bases.
▶️ A DNA sequence which is tandemly repeated in many copy numbers is called variable number tandem repeats (VNTR). It belongs to mini-satellite DNA.
Q 9: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (4) A-IV, B-III, C-II, D-I
▶️ Replication is the copying of DNA from parental DNA. It requires a set of enzymes such as DNA-dependent DNA polymerases.
▶️ Transcription is the copying of genetic information from one strand of the DNA into RNA. It starts with the help of initiation factor (σ factor).
▶️ Translation is the process of protein synthesis based on the sequence of codons in mRNA. It occurs in ribosomes.
▶️ Processing is the modification of heterogeneous nuclear RNA (hnRNA) into functional mRNA.
Q 10: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (1) A-IV, B-I, C-II, D-III
▶️ 2 nucleotides are linked through 3’-5’ phosphodiester bond to form dinucleotide. When more nucleotides are linked, it forms polynucleotide.
▶️ Negatively charged DNA is wrapped around histone octamer to give nucleosome.
▶️ 61 codons code for amino acids. 3 codons (UAA, UAG & UGA) do not code for any amino acids. They act as stop codons (Termination codons).
▶️ AUG has dual functions. It codes for Methionine and acts as initiator codon.
Q 11: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (2) A-III, B-IV, C-I, D-II
▶️ Homologous organs are the organs having fundamentally similar structure and origin but different functions. This phenomenon is called Homology. E.g., Human hand, Whale’s flippers, Bat’s wing & Cheetah’s foot. Thorns of Bougainvillea and tendrils of Cucurbita.
▶️ Development of resistant varieties in organisms against herbicides, pesticides, antibiotics or drugs etc. are the examples for natural selection by anthropogenic action (evolution due to human activities).
▶️ Adaptive radiation is the evolution of different species from an ancestor in a geographical area starting from a point and radiating to other areas of geography (habitats). E.g. Darwin’s finches in Galapagos Islands.
▶️ Genetic drift: The gene flow by chance causing change in frequency. Sometimes, the frequency change can lead to evolve into a different species. The original drifted population becomes founders. It is called founder effect.
Q 12: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (3) A-III, B-I, C-IV, D-II
▶️ 15 mya: Dryopithecus & Ramapithecus. Hairy. Walked like gorillas & chimpanzee.
▶️ 2 mya: Australopithecines. Lived in East African grass lands. Hunted with stone weapons. Ate fruits.
Homo habilis: First human-like being (hominid).
Brain capacity: 650-800 cc.
Did not eat meat.
▶️ 1.5 mya: Homo erectus (Java man). Large brain (900 cc). Ate meat.
▶️ 1 lakh - 40,000 yrs ago: Homo neanderthalensis (Neanderthal man).
Q 13: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (2) A-II, B-III, C-IV, D-I
▶️ Morphine is extracted from latex of Papaver somniferum (poppy plant). It is a sedative & painkiller. Used in surgery.
▶️ Heroin (smack or diacetylmorphine) is a white, odourless, bitter crystalline compound. It is obtained by acetylation of morphine.
▶️ Natural cannabinoids are obtained from inflorescences of Cannabis sativa (Hemp plant). Its flower tops, leaves & resin are used to make marijuana, hashish, charas & ganja.
▶️ Coca alkaloid or cocaine (coke or crack): It is obtained from coca plant Erythroxylum coca.
Q 14: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (3) A-II, B-I, C-IV, D-III
▶️ Cell-mediated immunity (CMI) causes Graft rejection. So, tissue matching and blood group matching are essential before undertaking any graft/ transplant.
▶️ Due to genetic and other unknown reasons, the body may attack self-cells resulting in damage to the body. It is called auto-immune disease. E.g. Rheumatoid arthritis.
▶️ HIV enters into helper T-cells (TH lymphocytes) → Replicates & produce progeny viruses → Attack other TH cells → TH cells decrease → Weaken immunity.
▶️ Cells sloughed from tumours reach other sites via blood where they form a new tumour. It is called metastasis.
Q 15: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (1) A-II, B-I, C-IV, D-III
▶️ Swiss cheese has large holes due to production of CO2 by Propionibacterium sharmanii.
▶️ Free-living bacteria in the soil (E.g. Azospirillum and Azotobacter) enrich the nitrogen content of the soil.
▶️ Methanogens grow anaerobically on cellulosic material and produce CH4. E.g. Methanobacterium.
▶️ Mycorrhiza: Symbiotic association of fungi (E.g. genus of Glomus) with plants. The fungus gets food from plant.
Q 16: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (4) A-II, B-III, C-IV, D-I
▶️ Biolistics (gene gun): It is a method to introduce alien DNA into host cells. In this, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA. This method is suitable for plants.
▶️ In gel electrophoresis, DNA fragments can be seen as bright orange-coloured bands when they are stained with ethidium bromide and exposed to UV radiation.
▶️ Polymerase Chain Reaction (PCR) is the synthesis of multiple copies of the gene of interest in vitro using 2 sets of primers & the enzyme DNA polymerase.
▶️ Downstream Processing: It is a series of processes such as separation and purification of products after the biosynthetic stage.
Q 17: Match List I with List II. 
(1) A-IV, B-I, C-II, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-IV, D-III
(4) A-IV, B-III, C-II, D-I
✅ (3) A-II, B-I, C-IV, D-III
▶️ Totipotency is the ability to generate a whole plant from any cell/explant. An explant is any part of a plant that is grown in a test tube under sterile nutrient media.
▶️ Somatic hybridization is the fusion of protoplasts from two different varieties of plants with desirable characters to get hybrid protoplasts.
▶️ ELISA (Enzyme Linked Immuno-Sorbent Assay) is a test to detect pathogenic antigens in the body. It is based on antigen-antibody interaction.
▶️ Biopiracy is the unauthorized exploitation of biological resources. E.g. Basmati rice.
Q 18: Match List I with List II. 
(1) A-I, B-II, C-IV, D-III
(2) A-II, B-III, C-IV, D-I
(3) A-II, B-I, C-III, D-IV
(4) A-I, B-II, C-III, D-IV
✅ (4) A-I, B-II, C-III, D-IV
▶️ Competition is a process in which fitness of one species (r value) is significantly lower in presence of another species. Here, both species are harmed (-).
▶️ Brood parasitism in birds: Here, the parasitic birds lay eggs in the nest of its host and lets the host incubate them.
▶️ Mutualism: In this interaction, both species are benefitted (+).
▶️ Commensalism: Here, one species is benefitted (+) and the other is unaffected (0).
Q 19: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (1) A-II, B-I, C-IV, D-III
▶️ Of the incident solar radiation, less than 50% is photosynthetically active radiation (PAR).
▶️ Tertiary consumers (secondary carnivores): Feed on primary carnivores. E.g. tiger, lion etc.
▶️ Fragmentation: It is the breakdown of detritus into smaller particles by detritivores (e.g. earthworm).
▶️ Grazing Food Chain (GFC): Here, primary consumer feeds on living plants (producer).
Q 20: Match List I with List II. 
(1) A-II, B-I, C-IV, D-III
(2) A-III, B-IV, C-I, D-II
(3) A-III, B-I, C-IV, D-II
(4) A-II, B-III, C-IV, D-I
✅ (2) A-III, B-IV, C-I, D-II
Causes of Biodiversity losses (The Evil Quartet)
▶️ Habitat loss and fragmentation: Most important cause. E.g. Tropical rain forests The Amazon rain forest is being cut for cultivating soya beans or for conversion of grass lands for cattle.
▶️ Over-exploitation: E.g., Stellar’s sea cow, Passenger pigeon etc.
▶️ Alien species invasions: Alien species cause decline or extinction of indigenous species. E.g. Nile Perch introduced in Lake Victoria (East Africa) caused extinction of over 200 species of cichlid fish.
▶️ Co-extinction: When a species becomes extinct, the species associated with it also extinct. E.g. In co-evolved plant-pollinator mutualism, extinction of one causes the extinction of the other.