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Biology (Medical Entrance) - 5

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Segments of DNA that can move to different positions in a genome of a cell are called

  1. alleles

  2. plasmids

  3. transposons

  4. codons


Correct Option: C
Explanation:

Transposons are also called jumping genes as they can jump or transpose to different locations in the genome of a single cell.

Opening of a flower and dropping of a bud are examples of

  1. movement of curvature

  2. epinastic movement

  3. hyponastic movement

  4. spontaneous movement


Correct Option: B
Explanation:

 This option is correct because epinasty means downward, differential growth of the upper or adaxial part of a plant organ. Auxin and ethylene are involved in this response.

An organism which is unable to produce a particular component required for its growth due to mutation is called

  1. prototroph

  2. bradytroph

  3. auxotroph

  4. strain


Correct Option: C
Explanation:

Auxotrophs require external addition of those components, which they are unable to synthesise.

Schwann cell is a part of the

  1. muscle cell

  2. nerve cell

  3. nephron

  4. liver cell


Correct Option: B
Explanation:

Schwann cells wrap nerve cell axons in the peripheral nervous system with layers of myelin (a type of plasma membrane that provides electrical insulation).

The third eyelid is vestigial and is called as nictitating membrane. What is its other name?

  1. Lacrimal sac

  2. Plica semilunaris

  3. Palpebrae

  4. Eyebrows


Correct Option: B
Explanation:

This option is correct because nictitating membrane is also known as plica semilunaris.

The process of breaking down of rhodopsin pigment is known as

  1. annealing

  2. ptosis

  3. bleaching

  4. quenching


Correct Option: C
Explanation:

This option is correct because in the presence of ultraviolet rays, rhodopsin breaks down and this process is known as bleaching.

Phototrophic movements of roots and stems are due to

  1. action of gravity

  2. effect of light

  3. differential hormonal effect

  4. epinasty and hyponasty


Correct Option: B
Explanation:

 This option is correct because phototropism is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth which response to a light stimulus.

Geotropic responses in the roots are due to

  1. inhibition of growth in the stem

  2. uniform growth on all sides of the root

  3. more growth on the upper side of the root

  4. more growth on the lower side of the root


Correct Option: C
Explanation:

This option is correct because geotropic responses in the roots occur due to more growth on the upper side of the root.

DNA cloning technique was invented by

  1. Mendel and Cohen

  2. Boyer and Cohen

  3. Boyer and Hargobind Khurana.

  4. Hershey and Chase


Correct Option: B
Explanation:

 Boyer and Cohen invented the DNA cloning technique that gave birth to an important branch of science called genetic engineering.

The movement of spermatozoids towards the neck of archegonium under the influence of chemical is known as

  1. chemotropism

  2. phototaxis

  3. chemotaxis

  4. hydrotropism


Correct Option: C
Explanation:

This option is correct because chemotaxis is the phenomenon in which somatic cells, bacteria and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment.  In multicellular organisms, chemotaxis is critical to early development (e.g. movement of sperm towards the egg during fertilization) and subsequent phases of development (e.g. migration of neurons or lymphocytes) as well as in normal function. 

 

Growth of cells that cause the plant stem to bend towards light is due to the unequal distribution of

  1. auxins

  2. enzymes

  3. cytokinin

  4. gibberellic acid


Correct Option: A
Explanation:

This option is correct because auxins are a class of plant growth substances and morphogens (often called phytohormone or hormone). Auxins have an essential role in coordination of many growth and behavioural processes in the plant's life cycle.

How nmany cranial nerves are found in frog?

  1. Six pairs

  2. Twenty pairs

  3. Ten pairs

  4. Twelve pairs


Correct Option: C
Explanation:

In a frog, the number of cranial nerves are ten pairs.      

Movement of cytoplasm is termed as

  1. Brownian movement

  2. Endocytosis

  3. Cyclosis

  4. Cytokinesis


Correct Option: C
Explanation:

 This option is correct because the movement of cytoplasm is termed as cyclosis or cytoplasmic streaming.

Response of a plant in turning towards the source of light is known as

  1. tropism

  2. habit

  3. climatic response

  4. none of these


Correct Option: A
Explanation:

This option is correct because movement of plant in response to an external stimulus is known as tropism. One of this stimulus can be a source of light to which the plants show response by bending. This process is known as phototropism.

In human brain, cerebral hemispheres are connected by

  1. corpus luteum

  2. corpora cardiaca

  3. corpus albicans

  4. corpus callossum


Correct Option: D
Explanation:

In human brain, cerebral hemispheres are connected by corpus callossum.

The centre of autonomic nervous system is located in

  1. hypothalamus

  2. cerebrum

  3. medulla oblongata

  4. cerebellum


Correct Option: A
Explanation:

The centre of autonomic nervous system is located in hypothalamus. 

One gene-one enzyme hypothesis was given by

  1. Beadle-Tatum

  2. Hershey-Chase

  3. Watson-Crick

  4. Avery-MacLeod-Mc Carty


Correct Option: A
Explanation:

 Beadle-Tatum worked on Neurospora crassa to show that one gene is responsible for producing one enzyme.

Stop codon is a nucleotide triplet in

  1. DNA

  2. t-RNA

  3. m-RNA

  4. r-RNA


Correct Option: C
Explanation:

 Stop codons are nucleotide triplets in m-RNA indicating termination of the process of translation.

The movement in plant organs in response to the force of gravity is known as

  1. heliotropism

  2. hydrotropism

  3. phototropism

  4. geotropism


Correct Option: D
Explanation:

This option is correct because geotropism is the movement of plant growth in response to the direction and force of gravity.

 

The leaflet of Oxalis exhibits

  1. phototropism

  2. hyponasty

  3. circumnutation

  4. nyctinasty


Correct Option: B
Explanation:

This option is correct because the leaflet of Oxalis exhibits hyponasty. Hyponasty is the increased growth of the lower surface of a plant part, resulting in an upward bending of the part.

The chemical stimuli causing the movement of antherozoids towards egg are

  1. malic acid and sugar

  2. succinic and malic acid

  3. citric acid and sugar

  4. sugar and succinic acid


Correct Option: A
Explanation:

This option is correct because the chemical stimuli causing the movement of antherozoids towards the egg are malic acid and sugar.

The innermost layer of meninges which is very close to brain is

  1. duramater

  2. piamater

  3. arachnoid mater

  4. mucosa


Correct Option: B
Explanation:

The innermost layer of meninges which is very close to brain is piamater.

A part of human brain which controls hunger, thirst and sleep is

  1. cerebrum

  2. cerebellum

  3. medulla

  4. hypothalamus


Correct Option: D
Explanation:

The part of human brain which controls hunger, thirst and sleep is hypothalamus.

The arrangement of ear ossicles of humans in the order starting from tympanum inwards is

  1. incus; stapes; malleus

  2. malleus; incus; stapes

  3. malleus; columella; incus

  4. stapes; malleus; incus


Correct Option: B
Explanation:

Malleus is the first bone, incus is the second and stapes is the third bone from tympanum to inner ear.

In human brain, the most abundant cell type is the

  1. motor neuron

  2. sensory neuron

  3. glial cells

  4. afferent neuron


Correct Option: C
Explanation:

In human brain, the most abundant cell type is the glial cells.

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