CUET 2023 Biology Question Paper with Answers & Solutions

Correct answer: D

Parthenogenesis (development of offspring from unfertilised eggs) occurs in rotifers, honeybees (drones develop from unfertilised eggs) and some lizards. It does not occur naturally in mammals.

Correct answer: D

Sponges, earthworms and leeches are hermaphrodites (bisexual, both sex organs in same individual). Cockroach is dioecious/unisexual with separate sexes.

Correct answer: B

Polyembryony - Orange (more than one embryo, e.g. citrus); Parthenocarpy - Banana (seedless fruit); False Fruit - Apple (thalamus contributes to fruit); Embryo Sac - Female gametophyte. So (A)-(III), (B)-(IV), (C)-(I), (D)-(II).

Correct answer: B

Dicot embryogeny: zygote -> globular -> heart-shaped -> mature/typical dicot embryo. Order = (C), (D), (A), (B).

Correct answer: D

Placenta secretes hCG, hPL, estrogen and progestogen. Luteinising hormone (LH) is secreted by the anterior pituitary, not the placenta.

Correct answer: D

(A) is wrong: first menstruation is menarche, not menopause. (B) is wrong: at ovulation LH is at peak, not progesterone. (C) is correct and (D) is correct (menopause around 50 years). So (C) and (D) only.

Correct answer: B

Sterilisation (tubectomy/vasectomy) is a terminal/permanent method of contraception. The others are temporary/reversible methods.

Correct answer: C

Lippes loop - Non-medicated IUD (III); Vaults - Barrier (I); Periodic abstinence - Natural method (IV); Progestasert - Hormone releasing device (II). So (A)-(III), (B)-(I), (C)-(IV), (D)-(II).

Correct answer: D

Griffith's transformation experiment sequence: live S kills mice (A); live R harmless (C); heat-killed S harmless (B); heat-killed S + live R kills mice showing transformation (D). Order = (A), (C), (B), (D).

Correct answer: C

Haemophilia, sickle-cell anaemia and phenylketonuria are Mendelian (single-gene) disorders. Down's Syndrome is a chromosomal disorder (trisomy 21), not Mendelian.

Correct answer: C

Metabolic Disorder - Phenylketonuria (III); Pedigree analysis - Family tree over generation (I); Thalassemia - Blood disease (II); Trisomy of 21st chromosome - Down's Syndrome (IV). So (A)-(III), (B)-(I), (C)-(II), (D)-(IV).

Correct answer: B

RNA is genetic material in some viruses (A); tRNA is adapter molecule (B); ribozymes are RNA catalysts (D). (C) is false: RNA has pentose (ribose), not hexose. So (A), (B) and (D) only.

Correct answer: D

Ribosome - Translation (III); Histone - Nucleosome (IV); DNA polymerase - Replication (I); RNA polymerase - Transcription (II). So (A)-(III), (B)-(IV), (C)-(I), (D)-(II).

Correct answer: B

An N-glycosidic linkage joins a nitrogenous base to the pentose sugar (forming a nucleoside). The sugar-phosphate link is a phosphoester bond.

Correct answer: D

Factors that disturb Hardy-Weinberg equilibrium: gene migration, genetic drift, mutation, genetic recombination and natural selection. Genetic equilibrium is the equilibrium state itself, not a disturbing factor.

Correct answer: B

A single-step large mutation that leads to speciation is called saltation (as proposed by Hugo de Vries).

Correct answer: C

Paleontological evidence is based on the study of fossils (remains of past organisms in rock strata).

Correct answer: B

Lymphoid Organ - Bone marrow and Thymus (III); Cancer - Carcinogens (IV); HIV - ELISA (I, diagnostic test); Typhoid - Widal Test (II). So (A)-(III), (B)-(IV), (C)-(I), (D)-(II).

Correct answer: A

(A) and (B) are true. (C) is false: allergy antibodies are IgE type, not IgA. (D) is false: adrenalin and steroids reduce (not enhance) allergy symptoms. Hence statements not true are (C) and (D) only.

Correct answer: A

Salmonella typhi - Typhoid (I); Streptococcus pneumoniae - Pneumonia (II); Rhino Viruses - Common cold (III); Plasmodium - Malaria (IV). So (A)-(I), (B)-(II), (C)-(III), (D)-(IV).

Correct answer: C

In mung bean, resistance to yellow mosaic virus and powdery mildew was induced through mutation breeding (NCERT).

Correct answer: D

Sterilized plant part - Explant (IV); Genetically similar plants - Somaclones (III); Meristem - Virus free culture (II); Somatic hybrids - Pomato (I). So (A)-(IV), (B)-(III), (C)-(II), (D)-(I).

Correct answer: A

Sonalika (and Kalyan Sona) are semi-dwarf HYV wheat varieties; Ratna is a semi-dwarf rice variety. So Wheat and Rice respectively.

Correct answer: C

Azotobacter, Oscillatoria and Nostoc are nitrogen-fixing organisms. Acetobacter is involved in acetic acid (vinegar) production and is not a nitrogen fixer.

Correct answer: C

The large holes in Swiss cheese are produced by large amounts of $CO_2$ released by the bacterium Propionibacterium sharmanii.

Correct answer: B

Nostoc, Anabaena and Oscillatoria are cyanobacteria. Glomus is a genus of mycorrhizal fungi, not a cyanobacterium.

Correct answer: B

Agarose is a natural polymer extracted from sea weeds (marine algae).

Correct answer: B

Cohen and Boyer constructed the first recombinant DNA by joining an antibiotic resistance gene with the plasmid (pSC101) of Salmonella; however NCERT states the first recombinant DNA was made using a plasmid from Salmonella typhimurium. NCERT line: 'The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid (autonomously replicating circular extra-chromosomal DNA) of Salmonella typhimurium.'

Correct answer: B

The antibiotic resistance gene acts as a selectable marker that helps select transformants (transformed cells) from non-transformants by growing them on antibiotic-containing medium.

Correct answer: A

cryIAc and cryIIAb control cotton bollworms; cryIAb controls corn borer. So cryIAb is not effective against cotton bollworms.

Correct answer: C

RNAi was used in tobacco plants to develop resistance against the nematode Meloidogyne incognita.

Correct answer: B

Biopiracy is the term for the use of bio-resources by MNCs and others without proper authorisation and compensatory payment.

Correct answer: D

Calotropis produces toxic cardiac glycosides which make it unpalatable, so it is not browsed/grazed by cattle. The other crops are eaten.

Correct answer: D

Differences in salt concentration between fresh water and sea water cause osmotic problems, so animals cannot survive long in the other medium.

Correct answer: C

Natural interconnection of multiple food chains forms a food web.

Correct answer: B

(A) is incorrect: primary carnivores are secondary consumers, not tertiary. (D) is incorrect: plants are producers, not primary consumers. (B) and (C) are correct. So incorrect statements are (A) and (D) only.

Correct answer: C

The Convention on Biological Diversity held at Rio de Janeiro in 1992 is also called the Earth Summit.

Correct answer: B

India's biodiversity hotspots include the Western Ghats, Himalaya, Indo-Burma region and Sundaland. Indo-Burma is the correct hotspot among the options.

Correct answer: B

Ozone thickness is measured in Dobson Units (DU).

Correct answer: A

Daily household/municipal waste is broadly biodegradable, plastic and non-biodegradable. Radioactive waste is not generated in daily human practice.

Correct answer: D

A complex life cycle of parasites involves one or two intermediate hosts that facilitate parasitisation of the primary host (NCERT).

Correct answer: C

Parasites harm the host by reducing its survival, growth, reproduction and population density (NCERT definition of parasitism's effect).

Correct answer: B

Cuckoo and Crow - Brood Parasitism (III); Copepods (on fish) - Ectoparasite (I); Plasmodium - Endoparasite (IV); Orchids on Mango tree - Commensal Organism (II). So (A)-(III), (B)-(I), (C)-(IV), (D)-(II).

Correct answer: C

Parasites tend to lose unnecessary organs (e.g. nervous, digestive systems), so (B) 'elaborate nervous system' is false. (D) is false since co-evolution means the parasite counteracts in the same host species, not shifts to another host. (A) and (C) are true. So not true = (B) and (D).

Correct answer: A

The liver fluke depends on two intermediate hosts (a snail and a fish) to complete its life cycle (NCERT).

Correct answer: D

Underground carbon stores are coal, oil and gas, and limestone/dolomite (sedimentary). CO2 is the atmospheric gaseous form, not an underground store.

Correct answer: B

Photosynthesis fixes atmospheric CO2 into organic matter, thereby decreasing CO2. Respiration, burning of forests and combustion of fossil fuels release CO2.

Correct answer: C

Nutrient cycling (movement of nutrients through biotic and abiotic components) is also called the biogeochemical cycle.

Correct answer: C

The oceans hold a large dissolved reservoir of carbon that buffers and regulates atmospheric CO2 levels (NCERT: oceanic reservoir regulates the amount of CO2 in atmosphere).

Correct answer: B

The amount of nutrients present in the soil at any given time is called the standing state (NCERT).