Biology Mock Test - NEET MCQ

Classes comprising animals like fishes, amphibians, reptiles, birds along with mammals constitute the next higher category called Phylum. All these classes are included in the phylum chordata. In case of plants, classes with a few similar characters are assigned to a higher category called Division.

All living organisms share common genetic material, i.e., DNA but with variations, e.g., bacteria have single stranded circular DNA while in highly evolved eukaryotic cells of plants and animals, DNA is a long double stranded helix.  

Viruses did not find a place in classification since they are not truly ‘living’ if we understand living as those organisms that have a cell structure. Viruses are neither prokaryotes nor eukaryotes. They are inert outside their specific host cell and cannot multiply of their own because they lack cellular machinery to use its genetic material. Viruses can only multiply in host or living cell.

Phycomycetes are the members of fungi that can thrive well on dead and decaying wood as saprophytes. These prefer to live in moist and damp places and need water for the  movement of zoospore and sexual gametes and Few members of phycomycetes are obligate parasites like Phytophthora. So option (d) is the correct answer.

Fruits can develop from a single ovary of a single flower (simple fruit) or from several free carpels of a single flower (aggregate) or from whole inflorescence (multiple). In total, fruits develop from ovaries. This is why a dioecious plant (unisexual) bearing only staminate(male) flowers will not produce fruits, whereas monoecious plants (bisexual) or dioecious plant bearing only pistillate (female) flowers or pistillate and staminate both can bear fruits.

A typical microsporangium is generally surrounded by four-wall layers, i.e., the epidermis, (outermost protective layer),endothecia, (middle fibrous layers) and the tapetum (innermost nutritive layer). 

The correct sequence of parts in an ovule are
Egg - embryo sac - nucellus - integument
(Inner)                                        (Outer)

Autogamy is pollination within a flower. Chasmogamous flowers are those in which anthers and stigma are exposed. For autogamy, in such a flower to take place, pollen and ovule should mature simultaneously and anther and stigma should lie close to each other.

Pollination by wind is called anemophily. Anemophilous flowers are small, in conspicuous non-scented without bright colours, nectar and fragrance. Wind pollination also requires that the pollen grains are light and non-sticky which is in large numbers and its stigmas are long and feathery.

Autogamy (same flower); geitonogamy (different flowers of same plants; xenogamy (different plant’s flower).
Dioecious plant bearing only male or female flowers prevents both autogamy and geitonogamy.

All the genes located on the same chromosome form one linkage group. A linkage group can be defined as all the genes on a single chromosome that move as a unit during the cell division. These genes do not tend to separate, until the crossing-over and if the distance between them is very less, they will not undergo the crossing-over. For examples, human beings have 23 linkage groups due to 23 pairs of chromosomes.

Hence, the correct answer is 'Form one linkage group'

Linkage is the phenomenon of physical association of genes on a chromosome and recombination is the generation of non-parental gene combinations. Strength of the linkage between two genes is inversely proportional to the, distance between the two, i.e., two linked genes show higher frequency of crossing over (recombination) if the distance between them is higher and lower frequency if the distance is small. But distance between gene has a direct relationship with percentage of recombination because with increase in distance between genes percentage of recombination increases.

So, the correct answer is 'A direct relationship'.

Both genes are equally expressed hence its codominance

Tt and Tt let's use Mendel's cross of tall and dwarf pea plants as an example. The  plants of genotype Tt are self-pollinated.(both tall (T) but with dwarf (t) alleles).  
The letters T and t are used to represent the alleles of the gene that determine plant height by conventions. The upper case letter (T) represents the dominant allele and the recessive allele (t) is represented by the same letter in lower case. Thus, the tall parents plants having heterozygous alleles, results in off springs which comprises of both tall and dwarf plants. For the parental cross, both the parents are true breeding plants, the tall plant is homozygous for the tall allele T, while the dwarf plant is homozygous for the dwarf allele 't'. Mendel tracked each trait through two generations. When true breeding plants were crossed to each other, this is called a parental cross and offspring comprise the first filial or F1 - generation. When the members of the F1 - generation were crossed, this produced the F2-generation or second filial generation. A cross between true breeding tall and dwarf plants of the parent generation yield phenotypically tall plants. The cross between TT and Tt is called back cross, which results into two homozygous and two heterozygous dominant gametes. The cross between Tt and tt is called testcross which results into 1:1 ratio of gametes.

Cross involving two contrasting characters is called dihybrid cross. The two flowers of each trait assort at random and independent of their traits at the time of meiosis (gametogenesis) and get randomly as well as independently rearranged in the offspring producing both parental and new combinations of traits. This explained the law of independent assortment given by Mendel.

So the correct option is "The alleles of two genes are segregating independently."

Mendal's Law of independent assortment tells us that the pairs of the alleles gets separated when the gametes are being formed that means the traits or characters that are being transferred to the offspring are independent.

Now the non homologous chromosomes are different from each other completely and they not take part in crossing-over.

Occasionally, a single gene may express more than one trait. This phenomenon is called pleiotropy. Sometimes, one trait will be very evident and others will be less evident, e.g., a gene for white eye in Drosophila also affect the shape of organs in male responsible for sperm storage as well as other structures.Similarly, sickle-cell anaemic individuals suffer from a number of problems, all of which are pleiotropic effects of the sickle-cell alleles. Multiple allelism is a series of three or more alternative or allelic forms of a gene, only two of which can exist in any normal diploid individual, e.g., genes of blood groups in humans. Mosaicism describes the occurrence of cells that differ in their genetic component from other cells of the body. Polygeny refers to a single characteristic that is controlled by more than two genes.(it is also known as multifactorial inheritance). 

In the F₂ generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are 4, 9 respectively.  

Two nucleotides are linked through 3 → 5 phosphodiester linkage to form a dinucleotide. More nucleotides are joined in a similar manner to form a polynucleotide chain.

Both deoxyribose and ribose belong to a pentoses class of sugars.

Sick / cell anaemia: It is a molecular disease, autosomal recessive disorder and an example of pleiotropy. It cannot be treated with iron supplements and it confers resistance to acquiring malaria.

It cannot be a double stranded DNA because as per Chargaffs rule for a dsDNA, The ratios between adenine and thymine and guanine and cytosine are constant and equal. Hence it is a ssDNA.

BOD of waste water is estimated by measuring the amount of oxygen consumption.

The technology of biogas production from cow dung was developed in India largely due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi & Village Industries Commission (KVIC) .

So, the correct option is 'Option C' .

Mycorrhiza help the host plant in enhancing its phosphorus uptake capacity, increasing its tolerance to drought and enhancing its resistance to root pathogens.

Salinity is the concentration of salt in water, usually measured in parts per thousand (ppt). The salinity of seawater in the open ocean is remarkably constant at about 35 ppt.

The entire ecosystem is made up of biotic and abiotic factors. Temperature, rainfall, snowfall, constitute some important abiotic factors. As we move from the equator to poles, the temperature range goes on decreasing and rainfall varies from place to place. At the poles, there is hardly any rainfall but snowfall is seen very regularly. Fir tropical rainforests to grow, the temperature in the range of 18-25 degree Celcius is required. Rainfall of around 150-400 cm is also required for the same.

So, option A is the correct answer.

A well growing herbaceous plant in the forest if it is transplanted outside the forest in a park. It may not survive because of change in its micro climate.

Initial population of paramecium P_i = 50
After one hour population of paramecium P_f = 150
Growth rate after one hour = P_f – P_i
= 150-50= 100

The parameters used for tiger census in our country's national park and sanctuaries are foot prints (pug marks) and faecal pallets of conserved animals.