Cell Structure

Question 1

• Extremely delicate, thin , elastic, living and semi-permeable membrane
• Maintains shape & size of the cell
  Protects internal contents of the cell

Answer 1

Plasma Membrane

Question 2

• Non-living and outermost covering of a cell (def)
• Prevents drying up(desiccation) of cells
• Helps in controlling cell expansion
• Protects cell from external pathogens

Answer 2

cell wall

Question 3

• Dense spherical body located near the centre of the cell
• Diameter varies from 10-25 µm
• DNA was found

Answer 3

Nucleus

Question 4

• Nucleus has a double layered covering called
• has pores of diameter
  about 80-100 nm

Answer 4

Nuclear Membrane

Question 5

Chromosomes contain stretches of DNA called

Answer 5

genes

Question 6

• Jelly-like material formed by 80 % of water

- Present between the plasma membrane and the nucleus

Answer 6

Cytoplasm

Question 7

• Network of tubular and vesicular structures which are interconnected with one another
• Gives internal support to the cytoplasm

Answer 7

Endoplasmic Reticulum

Question 8

synthesize secretory proteins and membrane proteins

Answer 8

Rough ER

Question 9

synthesize lipids for cell membrane

Answer 9

Smooth ER

Question 10

• Formed by stacks of 5-8 membranous sacs

- Delivers synthesized materials to various targets inside the cell and outside the cell

Answer 10

Golgi body

Question 11

• Small, spherical, single membrane sac

- Found throughout the cytoplasm

Answer 11

Lysosomes

Question 12

• Single membrane sac filled with liquid or sap (water, sugar and ions)
• Store various substances including waste products

Answer 12

Vacuoles

Question 13

Synthesize energy rich compound ATP

Answer 13

Mitochondria

Question 14

• double membrane-bound organelles found inside plants and some algae.
• storing food

Answer 14

plastids

Question 15

plastids that produce and store pigments

- gives color found in leaves, fruit…

Answer 15

Chromoplasts

Question 16

• colourless plastids that store foods.

- storage organs such as fruits, tubers etc

Answer 16

Leucoplasts

Question 17

• Convert light energy into chemical energy in the form of food
  
  • Double membrane-bound organelles found
    mainly in plant cells

Answer 17

Chloropasts

Question 18

• Help in the formation of cilia and flagella

- is the membrane bound organelle present near the nucleus

Answer 18

Centrosome

Question 19

• Give structural strength to the cell

- Responsible for cellular movements

Answer 19

Cytoskeleton

Question 20

the process by which a cell nucleus divides to produce two daughter nuclei containing identical set of chromosomes to the parent cell.

Answer 20

Mitosis

Question 21

is the process by which a cell nucleus divides to produce four daughter nuclei each containing half the number of chromosomes of the original nucleus or cell

Answer 21

Meiosis

Question 22

It is the division of cytoplasm.

Answer 22

Cytokinesis

Question 23

It is the period between successive cell divisions consisting of process associated with growth and preparation for mitosis

Answer 23

Interphase

Question 24

The karyokinesis has got four distinct stages as follows.

Answer 24

2. 1. Prophase
3. 2. Metaphase
4. 3. Anaphase
5. 4. Telophase
6. 1. Prophase

Question 25

Formation of spindle fibres is completed and chromosomes are attached to the spindle fibres at the point of centromere

Answer 25

Metaphase

Question 26

Chromosomes reach the opposite poles and spindle fibres begin to disintegrate

Answer 26

Telophase

Question 27

This is the shortest phase of the mitotic division

Answer 27

Anaphase

Question 28

1. Progressive condensation and coiling of chromosome fibres. 2. Chromosomes are scattered throughout the nucleus in a random manner.

Answer 28

Leptotene

Question 29

1. Chromosomes become shorter and thicker.

Answer 29

Zygotene

Question 30

Homologous chromosomes lie side by side and this pairing process

Answer 30

Synsapsis

Question 31

1. Exchange of chromosomal segments between non-sister chromatids of the homologous chromosome. This process is called crossing over.

Answer 31

Pachytene

Question 32

The point of exchange of chromatid during crossing over is called

Answer 32

chiasma.

Question 33

The homologous chromosomes are attached to each other by

Answer 33

chiasmata

Question 34

Separation of homologous chromosomes takes place from one another which begins from the centromere to end of the chromosomes

Answer 34

Diplotene

Question 35

1. This stage begins after the complete terminalization of chiasmata

Answer 35

Diakinesis

Question 36

It is a protein framework, which is found between paired chromosomes. It consists of one central and two lateral elements.

Answer 36

Synaptonemal complex