Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

71.

Golden rice is a transgenic crop of the future with the following improved trait

  • high lysine (essential amino acid) content

  • insect resistance

  • high protein content

  • high vitamin A content


D.

high vitamin A content

Generally seeds of rice do not have vitamin-A, but golden rice, which is developed through genetic engineering has the high vitamin-A content.


72.

In a type of apomixis known as adventive embryony, embryos develop directly from the

  • nucellus or integuments

  • synergids or antipodals in an embryo sac

  • accessory embryo sacs in the ovule

  • zygote


A.

nucellus or integuments

Apomixis does not involve gamete formation and fertilization is found in amphimixis. Adventive embryo formation is a type of apomixis in which embryos are formed from diploid integumental or nucellar cells.


73.

Bacillus thuringiensis (Bt) strains have been used for designing novel

  • bio- metallurgical technique

  • bio- mineralization processes

  • bio- insecticidal plants

  • biofertilizers


C.

bio- insecticidal plants

Bioinsecticides are those biological agents, which are used to control harmful insects. A bacterium, Bacillus thuringiensis is used for this purpose. Spores of this bacterium produce the insecticidal cry-protein. Therefore, spores, of this bacterium kill larvae of certain insects. The commercial preparations of B. thuringiensis contain a mixture of spores, cry-protein and an inert carrier.


74.

Why is vivipary an undesirable character for annual crop plants ?

  • It reduces the vigour of plant

  • The seeds cannot be stored under normal conditions for the next season

  • The seeds exhibit long dormancy

  • It adversely affects the fertility of the plant


B.

The seeds cannot be stored under normal conditions for the next season

Vivipary is the condition when seeds germinate on the plant. It is an undesirable character for annual crop plants because germinated seeds cannot be stored under normal conditions for the next season.


75.

Through which cell of the embryo sac, does the pollen tube enter the embryo sac?

  • Egg cell

  • Central cell

  • Persistant synergid

  • Degenerated synergid


D.

Degenerated synergid

Egg apparatus is present towards the micropylar end of an ovule. It has two lateral synergid cells and one centrally located egg cell. During entry of pollen tube within the ovule, synergid cells become disintegrate and provide path for entry of pollen tube within the chamber of embryo sac.


76.

Which one of the following represents an ovule, where the embryo sac becomes horse-shoe shaped and the funiculus and micropyle are close to each other?

  • Circinotropous

  • Anatropous

  • Amphitropous

  • Atropous


C.

Amphitropous

In an amphitropous ovule, the embryo sac becomes horse- shoe shaped and the funiculus and micropyle are close to each other. It is found in Alismaceae, Butamaceae families.

Circinotropous ovule- The nucellus and the axis are in the same line in the beginning but due to rapid growth on one side, the ovule becomes anatropous.

Anatropous ovule is a completely inverted ovule turned back 180°on its stalk.


77.

In order to find out the different types of gametes produced by a pea plant having the genotype AaBb, it should be crossed to a plant with the genotype

  • aaBB

  • AaBb

  • AABB

  • aabb


D.

aabb

Scientists perform test cross to find out the different types of gametes or the genotype of an unknown individual. Test cross is performed always between the F heterozygous plants and pure recessive (homozygous) parent plant. So, in the given case AaBb should be crossed with aabb.


78.

Using imprints from a plate with complete medium and carrying bacterial colonies, you can select streptomycin resistant mutants and prove that such mutations do not originate as adaptation. These imprints need to be used

  • only on plates with streptomycin

  • on plates with minimal medium

  • only on plates without streptomycin

  • on plates with and without streptomycin


A.

only on plates with streptomycin

Plates having streptomycin allow to propagate only those bacteria, which are resistant to the antibiotic.


79.

Photosynthetic Active Radiation (PAR) has the following range of wavelengths

  • 400- 700 nm

  • 450- 950 nm

  • 340- 450 nm

  • 500- 600 nm


A.

400- 700 nm

The cosmic rays, X-rays, UV-rays, the visible spectrum, infra red rays, radio waves, coming from sun are constituted electromagnetic spectrum. The waves of each of these types have a characteristic range of wavelengths. The visible spectrum, which is also known as Photosynthetic Active Radiation (PAR), has a range of wavelength of 380 nm to 760 nm. This part of electromagnetic spectrum is responsible for photosynthesis.


80.

Which of the following is generally used for induced mutagenesis in crop plants?

  • Alpha particles

  • X- rays

  • UV (260 nm)

  • Gamma rays (from cobalt 60)


D.

Gamma rays (from cobalt 60)

Gamma rays (from cobalt 60) is generally used for induced mutation in crop plants.