Explore topic-wise InterviewSolutions in Current Affairs.

Correct answer is (a) Torque

No. It can produce only rotatory motion.

A rigid body is the one which maintains its definite and fixed shape even when an external force acts on it.

(c) both (a) and (b)

Correct answer is (b) torque

Correct answer is  (d) none

Correct answer is (c) negligibly small

If no external torque acts on a body, then angular velocity will not be constant.

(a) forward direction

(b) backward direction

Rhizobium is present in the root nodules of leguminous plants. Theirs is a symbiotic relationship in which the bacterium obtains food and shelter from the plant and the plant gets fixed nitrogen in return. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.

It is a biological organism that fixes atmospheric nitrogen.

Cyanobacteria as biofertilisers

• They fix atmospheric nitrogen and increase the organic matter of the soil through their photosynthetic activity, e.g., Nostoc, Anabaena, Oscillatoria, etc.

• Blue-green algae increase the soil fertility by adding organic matter to the soil.

The symbiotic association of fungi and roots of higher plants is called mycorrhiza. The fungal hyphae absorbs phosphorus from soil and passes it to the soil and thus enriches the soil. It also protects plants by providing resistance from root-borne pathogens, tolerance to salinity and drought.

1. In nature, when there is chromosomal sex determination, usually 1 : 1 sex ratio is obtained. But there are other causes for deviation from 1 : 1 sex ratio. 

2. There are many other environmental sex determination methods where 1 : 1 sex ratio becomes skewed. This is due to mere chance of fertilization. 

3. Also some lower animals show parthenogenesis e.g. as in honey bees. In such cases, offspring produced may not be in 1 : 1 proportion.

When the carrying capacity of any habitat is exceeded there is severe resource crunch. This may be in the form of food, shelter or availability of mates. This results into struggle for survival. This will result into death of those who cannot cope up with the struggle. They may die due to starvation or due to interactions such as fierce competitions. This causes the population again to come back to equilibrium. Thus when carrying capacity is exceeded, the natural way is to reduce the population in the habitat.

The physical space of an organism with the other living or non-living factors is called its habitat.

The immediate surrounding of an organism is called microhabitat.

Correct answer is (a) Grinnell

Niche is defined as the processes about how that organism is linked with its physical and biological environment.

Correct answer is (a) community

Fundamental niche is the niche in the absence of all competitors, this is highly improbable in nature.

Ladybird, beetle and Dragonflies control mosquitoes and aphids.

As the science of genetics progressed, many changes were seen from Mendel’s generalizations. These are called as NeoMendelism. 

The deviations from Mendel’s findings can be categorised under following heads:

1. Intragenic interactions : These interactions : are seen between the alleles of same gene. e.g. incomplete dominance and co-dominance. They are also seen in multiple allele series of a gene. 

2. Intergenic interactions : Intergenic interactions are between the alleles of different genes present on the same or different chromosomes, e.g. pleiotropy, polygenes, epistasis, supplementary and complementary genes, etc.

Drosophila is most suitable organism because of the following reasons:

1. Drosophila cam easily be cultured under laboratory conditions. 

2. Life span of Drosophila is short for about two weeks.

3. Drosophila has high rate of reproduction and hence newer organisms can be obtained rapidly.

1. Down’s syndrome is caused due to aneuploidy. 

2. Aneuploidy is due to non-disjunction of chromosome at the time of gamete formation during meiosis. Due to nondisjunction, chromosomes fail to separate. 

3. In addition to a homologous pair of 21st chromosome there is an extra 21st, therefore it is called trisomy (2n + 1) of 21st chromosome.

Correct option is (a) Down’s syndrome = 44 + XY

Symptoms of Down’s syndrome:

1. Typical facial features. 

2. An epicanthal skin fold, over the inner corner of eyes causing downward slanting eyes. 

3. Typical flat face, rounded flat nose, mouth always open with protruding tongue. 

4. Mental retardation. 

5. Poor skeletal development. 

6. Short stature, relatively small skull and arched palate. 

7. Flat hand with simian crease that runs across the palm.

1. Klinefelter’s syndrome is a genetic disorder caused due to trisomy of X chromosome. 

2. It was first described by Harry Klinefelter. 

3. Klinefelter’s syndrome is caused due to non-disjunction of sex chromosomes which takes place during gamete formation. 

4. Chromosomal complement of Klinefelter’s syndrome is 44+XXY, having a total of 47 chromosomes.

Symptoms of Klinefelter’s syndrome are as follows: 

1. The Klinefelter’s syndrome individuals are tall, thin and eunuchoid

2. They are sterile with poorly developed sexual characteristics. 

3. Testes are underdeveloped and small. Spermatogenesis does not take place. 

4. They have subnormal intelligence and show partial mental retardation.

Haemophilia is due to a defective recessive allele located on the ‘X’ chromosome. In this disorder, a single protein which is involved in clotting of blood is affected. As a result, the individual bleeds even from a simple cut, that may become fatal.

1. Turner’s syndrome is a genetic disorder caused due to monosomy of X chromosome. 

2. It was first described by H. H. Turner. 

3. Turner’s syndrome is caused due to non-disjunction of sex chromosomes which takes place during gamete formation. 

4. Chromosomal complement of Turner’s syndrome is 44 + XO, having a total of 45 chromosomes.

Symptoms of Turner’s syndrome are as follows: 

1. Female phenotype. 

2. Short stature with webbing of neck. 

3. Low posterior hair line. 

4. Secondary sexual characters fail to develop. 

5. Mental retardation.

• 3:1 – Phenotypic ratio
• 1:2:1 – Genotypic ratio.

• Mendel studied one or two characters at a time for his breeding experiment
• He selected only those traits for his experiments which did not exhibit linkage or incomplete dominance.
• He performed the reciprocal crosses to confirm the validity of the correct ratio.
• He performed his experiment to F₂ + F₃ generation.
• He selected true breeding varieties of pea plant for cross pollination.
• He performed emasculation process to prevent self pollination.
• He maintained complete records of all his ‘ experiments and used statistical method and law of probability for analysing his results.
• He took great care in finding and choosing the true breeding plants genetically.

Short life span, only 4 pairs of chromosomes, distinct male & female traits, cultured in the lab.

Mendel selected pea plants on the basis of following characters:

• Pea plant exhibited number of contrasting characters.
• It normally undergoes self pollination but can be cross pollinated manually.
• It is an annual plant and yield’s result in a year’s time, so it can be observed for many generation.
• Many varieties were available with observable alternative forms for a trait.
• Pure varieties of pea were available which always bred true.
• Large number of seeds are produced per plant which can be easily handled and cultivated.

• The F hybrids always showed one of parental forms of the trait and there was no blending of traits.
• Both the parental form of traits appeared without any change / blending in the F₂ generation.
• The form of the trait appeared in the F₁ generation is called dominant character and it appeared in the F₂ generation about 3 times in frequency as that of its alternate form.

The phenomenon of failure of segregation of chromatids during cell division as a result of gain or loss of chromosome(s) is called aneuploidy.

a. Down‘s Syndrome 

b. Klinefelter‘s Syndrome 

c. Turner‘s syndrome

(a) 22 pairs of autosomes+XXY, Sterile male, poorly developed testis and mental retardation 

(b) Aneuploidy-failure of separation of chromosomes during cell division results in the gain or loss of chromosome.

Polyploidy – Failure of cytokinesis after telophase results in the increase in a whole set of chromosome

1. Alcoholic beverages are the products of alcoholic fermentation of particular substrates.

2. Tubular tower fermenters are used to produce alcoholic beverages on a large scale. 

3. Beer is produced from barley by fermentation. For the production of beer, strains of Saccharomyces cerevisiae are used. 

4. Wine is prepared from grapes. 

5. Whisky is prepared by fermenting mixed grains of wheat, barley and corn followed by the distillation of the products of fermentation. 

6. Liquors like beer, wine are produced without distillation. 

7. Whisky, rum and brandy are distilled alcoholic beverages. 

8. Toddy is prepared by fermenting the sugar sap extracted from palms and coconut palms. 

9. Fenny is fermented by fleshy pedicels of cashew fruits.

Aneuploidy is a phenomenon which occurs due to non-disjunction resulting into gain or loss of one or more chromosomes during meiosis.

Trisomic condition in human: Down’s syndrome.

Correct answer is (b) Wine, beer

Bread Mold: A dense cottony growth of fungus of Rhizopus on bread and other foods.

Whisky, brandy, rum