Master the CUET Bio Mock Test 4 with Ease

Right Answer Is B
Heterogamous organisms are those which produce two different types of gametes. In heterogamous organisms, the male gamete is quite small in size as compared to the size of the female gamete. The male gamete is known as the sperm and the female gamete is called the ovum or egg in heterogamous organisms.

Right Answer Is D
Thallophyta is a group of primitive land plants that includes fungi, lichens, and algae. These plants are simple as they have no roots, leaves, or stems. Bryophyta is a class of non-vascular plants that grow densely on the ground to form a carpet. These plants do not possess vascular tissue and rely on capillarity to move water up and down.
Pteridophytes are vascular plants, but their vascular tissues are primitive. They disperse spores and have hidden reproductive structures. All of these plant groups need water for fertilization. They produce flagellated male gametes which swim in the water to reach the non-motile female gamete.

Right Answer Is C
Most heterogamous organisms produce the motile male gamete, but the female gamete is non-motile. Heterogamous organisms have individuals of two different sexes, male and female. Male and female organisms produce different types of gametes. The male gamete is called sperm whereas the female gamete is called the egg or ovum.

Right Answer Is D
Sporopollenin forms the outer wall of pollen grains called exine. It is the highly resistant and non-degradable organic material known. It is non-degradable because it can withstand strong acids and high temperatures. There is no enzyme which can degrade sporopollenin.

Right Answer Is D
The pollen grain is enclosed in two layers, exine and intine. Intine is the inner layer made up of cellulose and pectin whereas exine is the outer layer made up of sporopollenin.

Right Answer Is C
A pollen grain has two cells. One is the vegetative cell or tube cell which forms a pollen tube during pollen germination. While another is the generative cell which divides to form two male gametes. The vegetative (tube) cell is larger in size because it stores an abundant amount of reserved food material. However, the generative cell is very small compared to the vegetative cell.

Right Answer Is A
About 60% of angiosperms shed their pollen in the 2-celled stage. Pollen at the 2-celled stage has both vegetative and generative cells in it. Generative cell divides to form two male gametes, in that case, pollen grains are said to be at a 3-celled stage.

Right Answer Is C
On the inside of each seminiferous tubule are two types of cells which are spermatogonia (male germ cells) and Sertoli cells. Sertoli cells are also referred to as nurse cells. The heads of spermatids get attached to Sertoli cells attached for nourishment during spermatogenesis

Right Answer Is C
Sertoli cells are supporting cells that provide nutrients to developing sperms, thus, they are also known as nurse cells.

Right Answer Is B
FSH (Follicle stimulating hormone) acts on the Sertoli cells and regulates their function i.e. stimulating the secretion of certain factors that aid in the process of spermiogenesis. The process of conversion of spermatids into motile sperm is known as spermiogenesis.

Right Answer Is A
Lactational amenorrhea is the total lack of menstruation during this period of intense lactation. Females go through a period of intense lactation after giving birth. Breastfeeding the child completely prevents conception during this stage.

Right Answer Is C
Rubber barriers such as diaphragms, cervical caps, and vaults are disposable contraceptives which are inserted into the female reproductive tract to conceal the cervix during coitus. Males cannot use these contraceptives.

Right Answer Is C
Spermicides are a type of contraception that is inserted into the vagina before sexual activity begins. They work by causing sperm damage and death in the vagina. Sometimes spermicidal creams are used in addition to condoms, cervical caps, diaphragms and vaults to increase the effect of contraception.

Right Answer Is B
In homozygous conditions, there is the same type of genes at the same locus in the genotype of an individual. However, the type of gene at the same locus in the genotype of an individual is different in heterozygous conditions.

Right Answer Is B
The number of gametes produced is determined by the number of heterozygous alleles found in a given genotype. The formula to find out the number of gametes is 2n, where ‘n’ is the number of heterozygous alleles present in the genotype. For example, in the case of genotype AABbCC (one heterozygous allele), two types of gametes (ABC and AbC) will be produced.

Right Answer Is A
The term “monohybrid” refers to the inheritance of only one contrasting trait by two parents at the same time. An example of a monohybrid cross is a cross between a tall (TT) and dwarf (tt) pea plant.

Right Answer Is B
Four offspring are produced in the F2 generation of a monohybrid cross. In Mendel’s monohybrid cross, F2 progeny have a phenotypic ratio of 3: 1. Three of the offspring have the dominant phenotype, while one has the recessive phenotype.
However, the genotypic ratio of Mendel’s monohybrid cross is 1: 2: 1 which means one individual from the F2 progeny is homozygous dominant (TT), two are heterozygous dominant (Tt), and one is homozygous recessive (tt).

Right Answer Is B
Griffith carried out the transformation experiment using R and S strains of Streptococcus pneumoniae. S-strain is generally pathogenic which causes the death of mice, whereas R-strain is not. Thus, only mice infected with strain-S died.

Right Answer Is D
Because genetic material must be passed down from generation to generation, it must be able to replicate. Because it codes the information for the organism’s survival and reproduction, it must be structurally and chemically stable.
It should be capable of going through slow mutations because slow or low mutation rates induce variability in the population, which can be advantageous for survival under adverse conditions and may also lead to genetic variability. It should be capable of expressing itself through Mendelian characters. As a result, the genetic material must meet all of these requirements. So, it is incorrect that an ideal genetic material should not express ‘Mendelian characters’.

Right Answer Is B
The Hershey and Chase experiment proved that DNA is the genetic material and protein is not. They showed that phosphorus is present in DNA but proteins contain sulphur which DNA lacks. In this experiment, they introduced a radioactive isotope of phosphorus (32P) into the DNA of one phage culture and a radioactive isotope of sulphur (35S) into proteins from a separate phage culture.
Because DNA contains phosphorus but proteins do not, viruses produced in the availability of radioactive phosphorus constituted radioactive DNA but not radioactive protein. Similarly, viruses cultivated on radioactive sulphur incorporate radioactive protein but not radioactive DNA because DNA is sulphur-free.

Right Answer Is C
Living organisms that share features of two different species and bridge the gap between them are referred to as link species. Lobe fish is an example of a link species. Around 350 million years ago, fish with stout and strong fins could relocate to land and return to the water.
These were known as lobes, and they diverged evolutionarily into the first amphibians that could live on both land and water, such as the coelacanth. The Dodo is a flightless bird that has become extinct. Chimpanzees are humans’ closest living relatives, and seaweed is multicellular marine algae.

Right Answer Is C
Chlorophyll might be evolved during the evolution of green algae and green plants evolved later than green algae. So, both chlorophyll and green plants cannot be the early energy source.
Similarly, carbon dioxide is a result of a photosynthesis reaction which is performed by chlorophyll-containing producers and for this reaction they also use sunlight as an energy source. This implies that UV rays and lightning from the sun are the possible early source of energy on earth. Also, Sun was the only energy source when there was nothing present on earth.

Right Answer Is A
Ancient Greek philosophers and Egyptians supported the theory of abiogenesis, believing that life evolved from abiotic components. They believed that frogs and snakes evolved from the mud of the Nile River. According to this theory, non-living things give birth to living organisms. As a result, this theory supports the spontaneous origin of life.

Right Answer Is B
When a man walks barefoot in soil, Ancylostoma enters his body through the skin of his foot. Ancylostomiasis is a disease in which this roundworm infects a person’s small intestine. Ascariasis is transmitted via hand-to-mouth contact, which occurs when a person touches and swallows fertilised Ascaris eggs.
Wuchereria infection occurs when filarial parasites are passed on to people via mosquitoes. Infection of Schistosoma occurs when larval forms of the parasite, released by freshwater snails, enter the skin during direct interaction with infested water.

Right Answer Is A
Filariasis is also referred to as elephantiasis due to the extreme enlargement of the legs. It is an infection of the lymphatic system that results in the swelling of infected organs like male genital parts, limbs, and mammary glands.

Right Answer Is D
William Harvey was the first to discover blood circulation in the human body. He was the first to properly describe the circulation of blood in the body. He demonstrated how arteries and veins work together to form a complete circuit.
The circuit begins at the heart and returns there. The regular contractions of the heart propel blood flow throughout the body. The cell was discovered by Robert Hooke, the nucleus of a cell by Robert Brown, and blood groups were discovered by Karl Landsteiner.

Right Answer Is C
In the case of pisciculture, induced breeding or hypophysation is used. This technique induces spawning in fish by using pituitary gland extract. It allows for spawning and the availability of fish seed at any time of year. Overall, hypophysation allows for the extraction of more fish from a single fish.

Right Answer Is B
Morus alba is the scientific name of the mulberry tree on which silkworm feeds. It basically feeds on the leaves of the mulberry tree.

Right Answer Is D
Karnataka is the state with the highest silk production. Mysore and North Bangalore are named “Silk City,” and they account for the majority of silk production. This state accounts for nearly 45% of the total mulberry silk production in India.

Right Answer Is C
Toddy is a traditional drink prepared in some parts of south India from palm sap fermentation. The sap from the palm tree’s base is collected and fermented using naturally occurring yeast to produce a beverage with an alcohol content of about 6%.

Right Answer Is B
In 1928, Alexander Fleming invented penicillin, the first antibiotic derived from the bacterium Penicillium notatum. Antibiotics are microorganism-produced chemical substances that can kill or prevent the growth of many other bacteria and fungi.

Right Answer Is D
The fermentation process is used to produce alcohol from malted cereals and fruit juices using Brewer’s yeast. Saccharomyces cerevisiae, also known as Brewer’s yeast, is used in alcoholic fermentation. Fermentation produces ethanol from malted cereals and fruit juices.

Right Answer Is C
In 1992, a four-year-old girl was treated first time with gene therapy for a genetic defect that caused a deficiency of an important enzyme i.e. ADA (Adenosine deaminase). It is a severe immune system deficiency. The therapy partially restored the patient’s immune system by replacing the defective gene in her blood cells with a functional variant.

Right Answer Is B
Genetic engineering is the process of modifying organisms’ genetic material (RNA or DNA) to use it to produce industrially valuable substances. The gene of interest is excluded from an organism’s cell and inserted into the vector DNA to construct recombinant DNA. For expression, the recombinant DNA is passed to the host cell.
Biotechnology is an approach that employs living organisms, like microorganisms, or enzymes derived from them, to create products that can benefit the living organism. Gene therapy refers to a method of treatment that involves modifying a person’s genes. The study of the structure and number of DNA inside the cell nucleus is referred to as cytogenetics.

Right Answer Is B
Retroviral vectors are made by substituting retroviral env, gag and pol genes with therapeutic genes and are used in gene therapy, which is the practice of inserting DNA into living humans to treat disease. It is used to fix mutant alleles or to substitute a missing gene product.

Right Answer Is C
Insulin is made up of two polypeptide chains which are chain A and chain B. Using rDNA technology, two DNA sequences corresponding to chains “A and B” are introduced into E. coli plasmids to produce insulin.

Right Answer Is A
A probe is a single-stranded and radioactively labelled DNA or RNA sequence. It is complementary to the gene of interest or target DNA segment and, due to its radioactivity, aids in the identification of the DNA sequence.

Right Answer Is D
To cut double-stranded (ds) DNA at palindromic sequences, different types of restriction endonucleases are used. They are known as restriction endonucleases because they trim the DNA within the molecule.

Right Answer Is A
Epiphytes are plants that grow on other plants while leaving the host unaffected. The climber is an epiphyte on its host plant. It gets space from the host plant which is neither harmed nor benefited. So, they exhibit commensalism which is an interaction between two species in which one is benefitted but the other remains unaffected.

Right Answer Is D
Ammensalism is a relationship between two species in which one suffers or is harmed while the other is unaffected.

Right Answer Is A
Commensalism is a relationship in which one organism benefits while others are unaffected. Cladophora alga grown on the snail shell cannot harm it but get space from the snail shell to live, thus, they exhibit commensalism.

Right Answer Is C
Only 10% of energy is passed to the next trophic level according to Lindeman’s 10% law. That means if the energy available at the first trophic level is 10,000 Joules, then the amount of energy passed to the second trophic level will be 1000 Joules which is 10% of 10,000 Joules.

Right Answer Is B
Critical elements are the macronutrients that are frequently deficient in soils. There are three of them which are nitrogen, phosphorus, and potassium. So, after nitrogen, phosphorous is the critical element for plant growth.

Right Answer Is C
Species composition is not a functional aspect of the ecosystem, it is the structural aspect. However, energy flow, decomposition and nutrient cycling are the functional aspects.

Right Answer Is C
Vulnerable species have populations that have recently declined and are continuing to decline, placing them at high extinction risk in the wild. Barasingha, Nilgiri Langur, Sloth bear, Yak, etc are some examples of vulnerable species.

Right Answer Is B
Rare species have a small number of members which live in a small geographical area, and are extremely uncommon, rare, or rarely encountered. For example, the Indian Giant Flying Squirrel, Gee’s Golden Langur, Dugong, Malabar Giant Squirrel, etc.

Right Answer Is A
Indeterminate species have members which are on the edge of extinction but the reason is unknown as there is incomplete information to assess their true nature. Examples include Rhinoceros, Sumatran short-eared rabbits, Brazilian three-banded armadillos, etc.

Right Answer Is A
The process of Earth’s atmosphere getting heated up is known as global warming. The rate of global warming has risen as greenhouse gas emissions have increased because these gases trap the heat of the sun and do not allow the earth to cool to the lowest possible temperature. Because the amount of greenhouse gas emissions are higher in the troposphere, the majority of the heat is trapped there. As a result of global warming, the heat in the troposphere rises.

Right Answer Is C
By trapping the sun’s heat, greenhouse gases contribute to keeping the earth warm at night. While it is critical to our survival, it also has some negative consequences. The presence of too many greenhouse gases raises the Earth’s average temperature, causing global warming.
Carbon Dioxide, Ozone, Methane, Water Vapour, and Nitrous Oxide are the major greenhouse gases recorded in the Earth’s atmosphere. Nitrogen, on the other hand, is not a greenhouse gas.

Right Answer Is B
Chlorofluorocarbons serve as a catalyst for the breakdown of the Ozone molecule to form one molecular oxygen and one nascent oxygen. The same reaction occurs in our atmosphere’s Stratosphere, where the Ozone layer is available. The presence of CFCs catalyses the ozone breakdown reaction, increasing its rate and thus, causing ozone depletion.