5.10 Nucleus

Question 1

The nucleus was discovered by ______ in ____ year.

Answer 1

Robert Brown; 1831

Question 2

The material of nucleus was stained by ___ (acidic/basic) dyes were given the name _____ by ______.

Answer 2

Basic; chromatin; Flemming

Question 3

The Interphase nucleus is -

Answer 3

Nucleus of a cell when cell is not dividing

Question 4

Interphase nucleus contains -

Answer 4

I. Chromatin
II. Nuclear matrix (nucleoplasm)
III. One or more sphrical bodies called Nucleoli (sing.: nucleolus)

Question 5

The Interphase nucleus has loose, highly extended and elaborate _______ fibers called Chromatin.

Answer 5

nucleoprotein

Question 6

The space between two parallel membranes of Nuclear envelope is of __-__ nm and is called ______ space.

Answer 6

10-15 nm; perinuclear space

Question 7

Perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm.
T/F

Answer 7

True

Question 8

The outer membrane bears ______ on it and remains continuous with -

Answer 8

Ribosomes; ER

Question 9

In nuclear envelope, Many minute nuclear pores form by fusion of -

Answer 9

Two nuclear membranes

Question 10

Through nuclear pores, movement of ______ and ______ take place in ______ (single/both) directions between nucleus and cytoplasm.

Answer 10

RNA and proteins; Both directions

Question 11

Does all cells have only one nucleus per cell?

Answer 11

No,
Variations in the number of nuclei are also frequently observed.

Question 12

Some mature cells even lack nucleus, e.g.,

Answer 12

I. Erythrocytes of many mammals
II. Sieve tube cells of vascular plants

Question 13

RBC doesn’t contain a nucleus hence it is non-living.
T/F

Answer 13

False,

Question 14

Nucleoplasm contains -

Answer 14

Nucleolus and chromatin

Question 15

Nucleoli are _____ shaped structures.

Answer 15

Spherical

Question 16

Nucleoli are membrane-bound.
T/F

Answer 16

False

Question 17

The content of nucleolus is continuous with the rest of the nucleoplasm.
T/F

Answer 17

True,
As Nucleolus is not a membrane bound structure.

Question 18

Nucleolus is the site for -

Answer 18

Active ribosomal RNA (rRNA) synthesis

Question 19

Larger and more numerous nucleoli are present in cells actively carrying out protein synthesis.
T/F

Answer 19

True,

Question 20

During different stages of ______, cells show structured ______ in place of the nucleus.

Answer 20

cell division; chromosomes

Question 21

Chromatin contains -

Answer 21

DNA, histones, some non-histone proteins & RNA

Question 22

A single Human cell has _____ m long thread of DNA, distributed among ____ chromosomes.

Answer 22

2 m long; 46 chromosomes (23 pairs)

Question 23

Chromosomes are visible only in ______ cells.

Answer 23

dividing cells

Question 24

Primary constriction is called ______ on the side of which disc shaped structures ______ are present.

Answer 24

Centromere; kinetochores

Question 25

______ (Centromere/Kinetochores) is the point that holds two chromatids of a chromosome.

Answer 25

Centromere

Question 26

Based on the position of the centromere, the chromosomes can be classified into four types:-

Answer 26

I. Metacentric
II. Sub-metacentric
III. Acrocentric
IV. Telocentric

Question 27

_______ chromosomes have centromere in the middle forming two equal arms.

Answer 27

Metacentric

Question 28

Acrocentric chromosomes have centromere slightly away from the middle forming one shorter arm and one long arm.
T/F

Answer 28

False,
sub-metacentric chromosomes

Question 29

Telocentric chromosomes have centromere at -

Answer 29

terminal end

Question 30

______ chromosome have centromere situated close to the end forming one extremely short and one very long arms.

Answer 30

Acrocentric

Question 31

Few chromoses have staining/non-staining secondary constriction at a constant/variable location.

Answer 31

Non-staining; constant

Question 32

Secondary constriction gives the appearance of a ______

Answer 32

Satellite