Biology: CUET Mock Test - 3 - CUET MCQ

The correct option is 'A - II, B - IV, C - I, D - III'.

Key Points

• Human skin colour is determined by Polygenic inheritance (II).
  • Polygenic inheritance refers to the inheritance of a phenotypic trait that is attributable to two or more genes and can be measured along a continuum.
  • Human skin color is an excellent example of polygenic inheritance, which is influenced by more than one gene and shows a wide range of phenotypes.
• A pair of alleles expressing contrasting traits refers to being Heterozygous (IV).
  • Heterozygous individuals have two different alleles for a given gene.
  • This condition often results in a phenotype that may express a dominant trait over a recessive one, illustrating the concept of dominance and recessivity in genetics.
• The ABO blood group system demonstrates Multiple allelism (I).
  • Multiple allelism occurs when three or more alleles for a gene exist within a population.
  • In the ABO blood group system, the A, B, and O alleles interact to produce the four blood types: A, B, AB, and O, showcasing multiple allelism.
• Antirrhinum flower colour is an example of Incomplete dominance (III).
  • Incomplete dominance occurs when the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.
  • For Antirrhinum (snapdragon) flowers, a cross between a red-flowered plant and a white-flowered plant results in offspring with pink flowers, demonstrating incomplete dominance.

Therefore, the correct pairing is:

A - II: Human skin colour - Polygenic inheritance

B - IV: Pair of alleles expressing contrasting traits - Heterozygous

C - I: ABO blood group - Multiple allelism

D - III: Antirrhinum flower colour - Incomplete dominance

Key Points

• The correct answer is option 3: (A), (C) and (D) only.
• This means the regions of the transcription unit include the Promoter, Terminator, and the Structural Gene.
• The Promoter is a region of DNA that initiates transcription of a particular gene. It is where the RNA polymerase binds to start transcription.
• The Terminator is a sequence of nucleotides in DNA that marks the end of a gene or operon in genomic DNA during transcription.
• The Structural Gene consists of the DNA sequence that is actually transcribed into RNA, which may then be translated into a protein.

Additional Information

• Sigma factor is not part of the DNA sequence of the transcription unit but rather a protein needed for the initiation of transcription in bacteria. It helps the RNA polymerase to bind to the promoter.
• Options 1, 2, and 4 are incorrect because they include the Sigma factor, which is not a region of the transcription unit but rather a transcription initiation factor.

Key Points

• Microbes play an important role for the production of industrial products.
• They are used for fermented beverages, antibiotics, bioactive molecules as well as food products like cheese.
• Microbes may include bacteria as well as fungi.
• Monascus purpureus is a type of yeast that is used to produce statins.
• Statins are blood cholesterol-lowering agents.
• It can induce competitive inhibition of the enzyme responsible for synthesis of cholesterol.

Additional Information

• Cyclosporin A -
  • ​It is produced from the fungus Trichoderma polysporum.
  • It is used as an immunosuppressive agent in organ transplant patients.
• Streptokinase -
  • ​It is produced from the bacterium Streptococcus.
  • It is used as a 'clot-buster' to remove unwanted blood clots in the blood vessels.
  • It is particularly useful in patients who have undergone myocardial infarction leading to heart attack.
• Acetic acid -
  • ​It is industrially produced from the bacterium Acetobacter aceti.

The correct answer is The energy and biomass relationship between the organisms at different trophic levels

• Ecological pyramids can determine the energy and biomass relationship between organisms at different trophic levels.
• These pyramids depict the flow of energy or biomass through the various levels of a food chain or food web.
• As you move up the pyramid, typically from producers (plants) to primary consumers (herbivores) to secondary consumers (carnivores), the energy or biomass available decreases, representing the loss of energy as it is transferred between trophic levels.

Additional Information An ecological pyramid is a pictorial representation of the relationship between different organisms in an ecosystem.

Pyramid of numbers:

• It depicts the numbers of individual organisms at different trophic levels of the food chain.
• It is helpful to calculate the changes observed in the number of organisms in each trophic level.
• We can identify which level is in the endangered zone and need to be saved. But its limitation is we cannot count a number of all organisms accurately.

Pyramid of Biomass:

• Biomass is the dry weight of the organism.
• Pyramid of biomass indicates a decrease of biomass in each trophic level from base to apex.
• With higher trophic level biomass decreases for ecosystem on land and its inverse for an aquatic ecosystem where biomass increases with higher trophic level.

Pyramid of Energy:
An energy pyramid shows how much energy is needed as it flows upwards to support the next trophic level. Here the pyramid is always upward.

Therefore, "The energy and biomass relationship between the organisms at different trophic levels" is the correct answer.

(A) Correct. Sex education in schools increases awareness about reproductive health, contraception, STIs, and safe practices, reducing misconceptions and promoting informed decisions.

(B) Correct. Family planning programs, such as those promoting contraceptives, sterilization, and education, aim to control population growth by enabling couples to plan family size and spacing.

(C) Incorrect. Female contraceptive options (e.g., pills, IUDs, implants, tubectomy, injectables) are more diverse than male options, which are primarily limited to condoms and vasectomy. Male hormonal contraceptives are still experimental.

(D) Incorrect. Surgical contraception methods (vasectomy and tubectomy) are highly effective but designed to be permanent. Reversal is possible in some cases (e.g., vasovasostomy or tubal ligation reversal), but success is not guaranteed, making “reversible” inaccurate.

(E) Correct. Medical Termination of Pregnancy (MTP) is legal in India under the MTP Act, 1971 (amended in 2021), but only under strict conditions, such as within 24 weeks (with exceptions), medical necessity, or consent, to prevent misuse.

(A) Correct: A Punnett square is used to calculate the probability of different genotypes in offspring.
(B) Incorrect: Genotype cannot always be determined from phenotype, especially in heterozygous organisms.
(C) Incorrect: The Law of Segregation (alleles separate into gametes) is distinct from the Law of Independent Assortment (genes assort independently).
(D) Correct: In co-dominance, both alleles are expressed equally, such as in the case of human blood types.
(E) Incorrect: The Law of Dominance applies when one allele is dominant over the other, regardless of whether the alleles are identical or not.

(A) Correct: Females have two X chromosomes (XX), which determine the female genotype.
(B) Correct: In the XY system, the presence of the Y chromosome determines male traits.
(C) Correct: Down's syndrome is caused by trisomy of chromosome 21, leading to an extra chromosome.
(D) Incorrect: Haemophilia is a sex-linked recessive disorder, but it is carried on the X chromosome, not the Y chromosome.
(E) Incorrect: Klinefelter’s syndrome is characterized by an extra X chromosome (XXY), not the absence of an X chromosome.

Pollination allows for the transfer of pollen from the anther to the stigma, which is essential for fertilization to occur.

After the pollen grain germinates on the stigma, it grows a tube down the style to allow sperm cells to travel towards the ovary.

The sperm cells travel through the pollen tube down to the ovary to fertilize the ovules.

After fertilization, the ovary matures into a fruit, which protects the developing seed and aids in seed dispersal.

If fertilization does not occur, the egg is absorbed, and the uterine lining is shed during menstruation.

Ovulation is the process where a mature egg is released from the ovary into the oviduct.

Tubectomy - Blocks gamete transport
Oral pills - Inhibit ovulation and implantation
Diaphragms - Prevent sperm from reaching an ovum
IUDs - Increase phagocytosis of sperms within the uterus

Home sapiens and Homo erectus in differ in their size of brain capacity. The size of brain of Homo erectus was smaller than Homo sapiens.

Darwin's Theory of Evolution (1) is associated with natural selection, which is the process of gradual change in species through survival of the fittest (C).
Lamarck's Theory of Evolution (2) is the idea that acquired characteristics (such as a giraffe's neck elongating) are passed down to offspring (A).
Fitness in Evolution (3) refers to an organism's ability to survive and reproduce based on inherited traits (D).
Natural Selection (4) refers to the process where variations that provide better adaptation to the environment are selected over time (B).

Malarial parasite requires two hosts - humans and mosquitoes to complete its life cycle. Mosquito acts as a primary host and human acts as a secondary host. Haemozoin is a toxic substance produced by the rupturing of red blood cells.

• Inflammatory response in allergy is due to the release of histamine by mast cells.
• Histamine along with IgE antibodies act as allergy mediator.
• It dilates arteries and causes fluid accumulation which causes the inflammatory response.

To correctly match List I (Diseases) with List II (Pathogen Types), we need to understand the causative agents for each disease listed in List I.

Details for each disease:

Typhoid: This is a bacterial infection caused by Salmonella typhi. Hence, it matches with "Bacteria".
Leishmaniasis: This disease is caused by parasitic protozoans of the genus Leishmania. Therefore, it corresponds to "Protozoa".
Ringworm: Despite its name, ringworm is not caused by a worm. It’s a fungal infection on the skin, caused by various types of fungi. So, Ringworm should be associated with "Fungus".
Filariasis: Also known as lymphatic filariasis, this condition is caused by infection with parasites classified as nematodes (roundworms) of the family Filarioidea. Thus, it matches with "Nematode".

With this understanding:
A should be paired with IV (Bacteria).
B should be paired with III (Protozoa).
C should be paired with I (Fungus).
D should be paired with II (Nematode).

Corresponding to the options provided:

Option A: A-I, B-III, C-II, D-IV - Incorrect
Option B: A-IV, B-III, C-I, D-II - Correct!
Option C: A-III, B-I, C-IV, D-II - Incorrect
Option D: A-II, B-IV, C-III, D-I - Incorrect

Therefore, the correct answer is Option B: A-IV, B-III, C-I, D-II.

In stage - I, anaerobic microorganisms bring about enzymatic breakdown of complex organic compounds into simple soluble compounds or monomers.
In stage - II, monomers are converted into organic acids by fermentation causing microbes.
In stage - Ill, organic acids are acted upon by methanogenic bacteria to produce biogas.

An example of microbial biocontrol agent is bacteria Bacillus thuringiensis (Bt).
It can be introduced in order to control butterfly caterpillars.
These are available in sachets as dried spores that are mixed with water and sprayed onto vulnerable plants such as Brassica and fruit trees, where these are eaten by the insect larvae. In the gut of larvae, the toxin is released and the larvae get killed. The bacterial disease will kill the caterpillars, but leaves other insect uharmed. 

Option (3) is the correct answer because cellulase is used to isolate genetic material from plant cells and chitinase is used to isolate genetic material from fungal cells.

Option (2) is incorrect because protease is used for digestion of proteins.

Option (1) and (4) are incorrect because lipase is used for the breakdown of lipids.

Both the statements are correct but the given reason is not the correct explanation. Polymerase chain reaction is used in DNA amplification.

Ampicillin resistance gene is a selectable marker that helps to check transformation by selection of transformants.

Rice is a staple food in many countries, particularly in Asia, but does not contain vitamin A or its immediate precursors. By inserting two genes from Daffodil and one gene from a bacterial species into rice plants, Swiss researchers have produced rice capable of synthesising β-carotene, the precursor of vitamin A. Vitamin A is required by all individuals as it is present in retina of eyes. Deficiency of vitamin A causes night blindness and skin disorders. This rice is called 'Golden rice' because of yellow colour of rice grains due to the presence of β-carotene.

A represents polypeptide chain C which is removed prior to insulin formation

Topic in NCERT: Genetically engineered insulin

Line in NCERT: "insulin consists of two short polypeptide chains: chain a and chain b, that are linked together by disulphide bridges."

S-shaped growth curve is also called Verhulst-Pearl logistic curve and is represented by the following equation :

where dN/dt= rate of change in population size, r= intrinsic rate of natural increase, N= population density, K= carrying capacity and 

Topic in NCERT: Logistic Growth

Line in NCERT: "This type of population growth is called Verhulst-Pearl Logistic Growth and is described by the following equation: dN/dt = rN(K-N)"

CominensaHsm is the relationship between two living individuals of different species in which one is benefitted while other is neither harmed nor benefined, e.g., Small fish (sucker fish) gets stuck near the bottom of a shark with the help of it's hold fast (modified dorsal fin) and is dispersed to distant areas. It also gets protection and derives its nutrition also and shark does not get any benefit or harm. Predation is an association between members of two species in which members of one species capture, kill and eat up members of other species, e.g.. Insectivorous plants like Drosera. Antibiosis : in this one organism inhibit growth of other organism through the secretion of antibiotics. This is based on biological antagonism and also known as allelopathy, e.g.. Smoother crops e.g.. Barley rye, millets are those which do not allow weeds to grow near by. Parasitism: in this type of association one member is benefitted. (parasite) and other is harmed (host), e.g.. Parasitic bacteria, viruses.

Topic in NCERT: Commensalism

Line in NCERT: "The interaction in which one species benefits and the other is neither harmed nor benefited is called commensalism."

Let's evaluate each statement:
A. Detrivores perform fragmentation.
This statement is true. Detrivores, such as earthworms and beetles, break down detritus (dead organic material) into smaller pieces in a process called fragmentation.

B. The humus is further degraded by some microbes during mineralization.
This statement is true. Microbes, including bacteria and fungi, break down humus into inorganic nutrients in a process called mineralization.

C. Water-soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching.
This statement is true. Leaching refers to the process where nutrients are washed away from the soil into lower layers or into bodies of water.

D. The detritus food chain begins with living organisms.
This statement is false. The detritus food chain begins with dead organic material or detritus, not living organisms.

E. Earthworms break down detritus into smaller particles by a process called catabolism.
This statement is false. The process by which earthworms break down detritus into smaller particles is called fragmentation, not catabolism. Catabolism refers to the breakdown of complex molecules in living organisms to form simpler ones, along with the release of energy.

Therefore, the correct answer is : Option A: A, B, C only.

Topic in NCERT: Decomposition

Line in NCERT: "this process is called fragmentation. by the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. bacterial and fungal enzymes degrade detritus into simpler inorganic substances. this process is called as catabolism. humification and mineralisation occur during decomposition in the soil. humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. the humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation."

In the equation GPP - R = NPP,
GPP stands for Gross Primary Productivity, NPP stands for Net Primary Productivity, and R represents the energy used by plants for their own metabolic processes, which is also known as Respiratory loss.

Topic in NCERT: Primary productivity

Line in NCERT: "gross primary productivity minus respiration losses (r), is the net primary productivity (npp).
Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP). GPP – R = NPP Net primary productivity is the available biomass for the consumption to heterotrophs (herbiviores and decomposers)."