Biology (Class - XII)

 Rhizopus stolonifer helps in the production of commercial drugs using alcohol. 

Heterogamy is the fusion of two different types of gametes. Thus, this is the correct answer.

Yes, this is the correct answer as some possible ill-effects seen on using contraceptive methods are nausea, abdomen pain, irregular menses and breast cancer.

Bhopal gas tragedy, an environmental disaster, is associated with the leakage of methyl isocyanate (MIC).

The human population curve has a J shape.

It is the correct answer.

Vestigial organs were useful in the past, but are useless now.

Snow blindness or the inflammation of cornea of the eye is caused by a high dose of UV-B radiation.

Chlorella, Spirulina and Yeasts are used as single cell proteins.

This is the correct option. Holstein-Friesian is the highest milk-yielding variety of cows. It can give 16,000 litres of milk in its lactation period.
This is a wrong option. The correct option is Holstein-Friesian.

Restriction enzymes, also known as restriction endonucleases, are enzymes that cut a DNA molecule at a particular place.

In angiosperms, male gametophyte consists of a tube cell and a generative cell. The generative cell divides to form two male gametes.

Okazaki fragments are short DNA fragments on the lagging strand. Synthesis of the lagging strand requires working in relatively small, discontinuous stretches. These discontinuous stretches are synthesised just as the leading strand, by the addition of new nucleotides one at a time to the 3′ end of the new strand, but the synthesis of this new strand moves in the direction opposite to that in which the replication fork is moving. These stretches of new DNA for the lagging strand are called Okazaki fragments.

SLE is a disease involving antibodies to non-organ specific antigens such as DNA and induces immune complexes, which deposit in the vascular bed causing kidney, skin, joint and cerebral lesions.

Sperms released from the seminiferous tubules are transported by the accessory ducts. Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for maturation and motility of sperms.

In milkweeds, sticky cente of two adjacent pollinia is called corpusculum. It makes a stick base of pollinium.

Amazon forests are known as the ‘lungs of the planet Earth’.

In 1942, Lindemann put forth the famous ten percent law for the transfer of energy from one trophic level to another in a food chain.

Human height and skin colour are controlled by many genes.

When there is no repressor on the operator, RNA polymerase, which is on the promoter, moves to the structural genes to transcribe them.

It is the causal agent of amoebiasis and is more commonly found in males than females.

Correct answer.
The enzyme that cuts the bonds of DNA molecule at the origin of replication is restriction endonuclease.
The enzyme required to release the tension imposed by uncoiling of strands is DNA gyrase.

Correct sequence: Juvenile phase-Reproductive phase-senescent phase

Progesterone levels are not at peak during ovulation period.

Intrauterine contraceptive devices; these devices have a risk of perforation in the uterus.

Phrap is a widely used program for DNA sequence assembly. 

This is the correct choice. It is Bacillus thuringiensis.

The immediate surrounding area of a core zone is buffer zone. Here, limited human activities like research, education and research strategy are permitted.

The Biological Diversity Act, 2002 is an act of the Parliament of India for the preservation of biological diversity in India and provides mechanism for equitable sharing of benefits arising out of traditional biological resources and knowledge. The Act was enacted to meet the obligations under Convention on Biological Diversity (CBD), to which India is a party.