Cell: Unit Of Life

Question 1

What is a cell?

Answer 1

A cell is a structural and functional unit of all living beings

Question 2

The first microscope was created by?

Answer 2

Antony Van Leeuwenhoek

Question 3

Simple microscopes consisted?

Answer 3

Single Biconvex lens

Question 4

Who created a microscope with 2 lenses?

Answer 4

Robert Hooke

Question 5

State the 3 main points of cell theory.

Answer 5

1.The cell is the smallest unit of structure of all living things
2. The cell is the unit of function of all living things
3. All cells arise from pre-existing cells.

Question 6

Name some single-celled organisms

Answer 6

Bacteria , Amoeba, Yeast

Question 7

Name some few-celled organisms

Answer 7

Spirogyra, Volvox

Question 8

Name some multi-celled organisms

Answer 8

Human beings, Mango

Question 9

The smallest cell

Answer 9

Bacteria, RBC

Question 10

Longest cells

Answer 10

Nerve cells

Question 11

Largest cells

Answer 11

Bird’s eggs, ostrich eggs

Question 12

Why are cells small in size?

Answer 12

1. different regions can communicate with each other rapidly for the cell to function effectively
2. Cells have large surface area/volume ratio for greater diffusion of substances in and out of the cell.

Question 13

Shape of Human RBC

Answer 13

circular and biconcave( to pass through narrow capillaries and transport o2)

Question 14

Shape of WBC

Answer 14

Amoeboid(squeeze out through capillary walls)

Question 15

Shape of Nerve cells

Answer 15

long(to conduct impulses)

Question 16

Shape of Muscle cells

Answer 16

long and contractile( to pull or squeeze the parts)

Question 17

Shape of Guard Cells

Answer 17

bean shaped( to open and close the pores)

Question 18

Differentiate between cell wall and cell membrane

Answer 18

Cell membrane-
1. Fine pores through which substances may enter or leave the cell.
2. Permeability is selective
CELL WALL-
1. Plants have cell wall
2.Gives shape and rigidity
3. Freely permeable

Question 19

Explain cytoplasm

Answer 19

1.Semi-liquid substances
2.Colourless,partly transparent and somewhat watery
3.Many chemical reactions take place here
4. Living cytoplasm

Question 20

Explain Endoplasmic Reticulum

Answer 20

1.Revealed only through an electron microscope
2.ER is an irregular network of double membranes distributed over the entire cytoplasmic
3. At the outer end E.R is connected with the cell membrane
4.In the inner end it is connected with the nuclear membrane
5. It appears rough with ribosomes but smooth without it.
6. it forms a supporting framework of the cell and also serves as a pathway for the distribution of the material from one part of the cell to another.

Question 21

Explain ribosomes

Answer 21

1. Numerous small granules
2. Either scattered freely in the cytoplasm or attached to the E.R
3. These are factories for the synthesis of protiens.

Question 22

Explain Mitochondria

Answer 22

1. Spherical, rod-shaped or thread like structures
2. Double walled bags with thier inner wall produced into finger like processes projecting inwards.
3. It is where cell respiration occurs to release energy.
4. The energy is stored in the form of ATP. Atp is used in various metabolic functions of the cells

Question 23

Explain Golgi Apparatus

Answer 23

1. Granules, Filaments or rods
2. They are supposed to originate from the E.R
3. Usually located near the nucleus
4. It is concerned with the sectretions of the cell including enzymes and hormones

Question 24

Explain Lysosomes

Answer 24

1. Contain digestive enzymes
2. Their enzymes destroy and digest foreign substances around them.
3. The digest the stored food during starvation of the cell.
4. Many damaged cells are repeatedly destroyed or dissolved by their own lysosomes and hence these are called “sucide bags”

Question 25

Centrosomes and Centrioles

Answer 25

1. Centrosomes are only found in animal cells 2. The centrosomes contain 2 centrioles which are small bundles of microfilaments arranged at right angles to each other. 3. These are not present in plant cells.

Question 26

Explain plastids

Answer 26

1. only found in plant cells 2. There are divided into 3 based on the colour - Leucoplasts(White) -Chromoplasts(Yellow,orange and red) -Chloroplasts(Green)

Question 27

Explain Leucoplasts

Answer 27

1. Colorless plastids 2.Have no pigment 3.Store Starch 4.Cells of potato have lots of leucoplasts in them

Question 28

Explain Chromoplasts

Answer 28

1. Present in petals of flowers and fruits 2.xanthophyll- yellow 3. Carotene- Orange and red

Question 29

What are anthocyanins?

Answer 29

Anthocyanins are a group of pigments found in plants that give them their red, purple, and blue colors.

Question 30

Explain chloroplasts

Answer 30

- They have chlorophyll -Function: Trap solar energy and absorb carbon dioxide for the manufacture of starch and sugar during photosynthesis - They contain DNA and the capacity to divide

Question 31

Are granules living or non-living? Explain

Answer 31

Nonliving. They are present in the cytoplasm and contain food materials such as starch glycogem and fats

Question 32

Vacuoles

Answer 32

-Cytoplasm -In plant cells they are large and contain cell sap - certain clear spaces in the cytoplasm

Question 33

Nucleus Functions

Answer 33

- Regulates and co-ordinates various life processes - Plays and imp part in the cell div - Contains genes

Question 34

Explain chromatin fibres

Answer 34

- Thread-like - Present in nucleoplasm - During cell div they become thick and ribbon -like and are called chromosomes

Question 35

What does the nucleolus do?

Answer 35

Partcipare in protien synthesis of ribosomes

Question 36

What is protoplasm?

Answer 36

It is the total living substance that is the cytoplasm and nucleus. It is a translucent fluid somewhat colourless, geyish or brown

Question 37

Composition of protoplasm

Answer 37

C,O,H,N,S,Fe all present in specifci compouns like water, protiens, carbs, fats and mineral salts