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Structure and Functions of Cell

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Which statement is not true for karyotype?

  1. It provides information about chromosome number, relative size, position of centromere, etc.

  2. It is described in the form of idiogram.

  3. C-banding brings about AT rich region.

  4. Cells are treated with colchicine at metaphase.


Correct Option: C
Explanation:

It stains regions having constitutive heterochromatin. Q-banding shows AT rich regions.

In which of the following would you expect to find glyoxysomes?

  1. Root hairs

  2. Endosperm of wheat

  3. Palisade cells in leaf

  4. Endosperm of castor


Correct Option: D
Explanation:

Glyoxysomes are microbodies found in seeds and possess enzymes capable of mobilising lipids, converting them into sugars to supply energy needed during germination. Hence, they are found in castor endosperm.

In case of mitosis in 'Gnetum', which of the following is the correct explanation for the term ‘karyochoresis’?

  1. During cell division, the karyotheca disappears completely.

  2. During cell division, the karyotheca and the nucleolus disappear completely.

  3. During cell division, the karyotheca does not disappear.

  4. During cell division, the mitotic spindle is not formed.


Correct Option: C
Explanation:

Karyochoresis is that type of mitosis in which the nuclear membrane (karyotheca) does not disappear, but it persists throughout the cell division and it can be seen even at the telophase. During karyochoresis, the spindle formation is internal. After telophase, the parent nucleus undergoes centripetal constriction and divides into two daughter nuclei.

Colchicine is a root extract of Colchicum autumnale. It inhibits cell cycle during the stage of

  1. G1 phase

  2. S phase

  3. M phase

  4. G2 phase


Correct Option: C
Explanation:

Spindles are formed during metaphase of M phase. These spindles are made of tubulin dimers. Cochicine disrupts tubulin dimers and cell cycle gets arrested. Thus, this option is the correct.

Which of the following statements is not true about cell theory?

  1. The bodies of all living beings are made up of cells and their products.

  2. Cells are the structural units in the body of a living organism.

  3. Every cell is made up of a small mass of protoplasm having nucleus.

  4. All organelles of cell can survive individually.


Correct Option: D
Explanation:

A cell can survive independently but not its organelles.

Which of the following pairs of scientist and discovery is incorrectly matched?

  1. Meischer - Nucleotides

  2. Holler et al - Structure of tRNA

  3. Nageli and Cramer - Cell membrane

  4. Robert Brown - Nucleus


Correct Option: A
Explanation:

Nucleotides of DNA were first discovered by Oswarld Avery.

Which of the following types of enzymes catalyses the reaction inolving the binding of two compounds with breaking up of pyrophosphates?

  1. Ligase

  2. Lyase

  3. Transferase

  4. Hydrolase


Correct Option: A
Explanation:

As the name indicates, it ligates (join) the substrate molecules.

Consider the following statements:

Segmental allopolyploids are the polyploids in which

  1. the chromosomes are derived from different genomes
  2. the chromosomes form multivaluents during meiosis
  3. the genomes involved are not quite different from one another

Which of the statements given above are correct?

  1. Only 1 and 2

  2. Only 2 and 3

  3. Only 1 and 3

  4. All of the above


Correct Option: C
Explanation:

 The correct answer is option no.3.

Raffinose is a trisaccharide found in cotton seeds and lima beans. The component sugars of raffinose are

  1. arabinose, glucose and fructose

  2. fucose and galactose

  3. glucose, fructose and galactose

  4. mannose, glucose and galactose


Correct Option: C
Explanation:

D-glucose, D-fructose and D-galactose are the residues obtained on acid hydrolysis of raffinose.

Which of the following are amphipathic glycosides?

  1. Polyphenols

  2. Phytosterols

  3. Alkaloids

  4. Saponins


Correct Option: D
Explanation:

Saponins is a class of chemical compounds, one of many secondary metabolites found in natural sources with saponins found in particular abundance in various plant species. Specifically, these are amphipathic glycosides grouped phenomenologically by the soap-like foaming they produce when shaken in aqueous solutions.

Colchicine is employed to diploid a haploid cell as it

  1. inhibits karyokinesis

  2. inhibits formation of mitotic spindle

  3. allows replication of DNA twice in one cell cycle

  4. inhibits formation of centromere


Correct Option: B
Explanation:

Colchicine, a drug, which inhibits spindle fibre formation during mitosis and halts cell division at metaphase. This often will result in a doubling of the chromosome number since colchicine typically inhibits cytokinesis, but not karyokinesis. The doubled chromosomes will fuse within a single nucleus, thus diploidising the haploid cell.

By which of the following processes an amino group from amino acid is transferred to produce a keto acid?

  1. Condensation

  2. Transamination

  3. Deamination

  4. Hydrolysis


Correct Option: B
Explanation:

In transamination, transfer of an amino group by transaminase from an amino acid takes place, producing keto acid.

The role of the nucleus in regulating the phenotype of plant was discovered in

  1. maize

  2. Neurospora

  3. Acetabularia

  4. pea


Correct Option: C
Explanation:

The control of nuclei over the phenotypic expression of the cell was studied in Acetabularia.

Which of the following sterols is a precursor to vitamin D2?

  1. Stigmasterol

  2. Ergosterol

  3. Campesterol

  4. Brassicasterol


Correct Option: B
Explanation:

Ergosterol is a biological precursor (a provitamin) to vitamin D2. It is turned into viosterol by ultraviolet light and is then converted into ergocalciferol which is a form of vitamin D. It does not occur in plants or animal cells, but it is a component of yeast and fungal cell membranes serving the same function that cholesterol serves in animal cells.

Which of the following processes takes place during the G2 phase of cell division?

  1. Synthesis of RNA, proteins, nucleotides and amino acids

  2. Synthesis of factors required for initiation and completion of mitosis and checks for any abberrations resulting from DNA synthesis

  3. Synthesis of RNA and proteins leading to the growth of cell to normal size

  4. Synthesis of DNA leading to chromosomal replication


Correct Option: B
Explanation:

All these changes occur in G2 phase and halts to complete this process.

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