Name the cell organelles which:
(i) initiates and regulates cell division.
(ii) traps solar energy.
(iii) concerned with ATP production.
(iv) regulates the entry of cell solutes and ions.
Answer
(i) Centrosome
(ii) Chloroplast
(iii) Mitochondria
(iv) Cell membrane (Plasma membrane)
Name the longest cell found in human body.
Answer
Nerve cell.
Name the largest cell found in human body.
Answer
Ovum.
Centrioles :
- Found only in plant cell
- Found inside nucleus
- Found only in animal cells
- Found in animal and plant cell
Answer
Found only in animal cells.
Reason — Centrioles are present within the centrosome, which lies near the nucleus in animal cells. They are absent in plant cells. Hence, centrioles are found only in animal cells.
Cell wall :
- Regulates entry of solutes in plant cells
- Regulates entry of solutes in animal cells
- Gives rigidity and shape to plant cells
- Gives rigidity and shape to animal cells
Answer
Gives rigidity and shape to plant cells.
Reason — The cell wall is a non-living, rigid layer made up of cellulose and is found only in plant cells. It provides rigidity and a definite shape to the plant cell. Being freely permeable, it does not regulate the entry of solutes.
Priya attempted to match various cellular components with their corresponding functions.
| Cellular Component | Function |
|---|---|
| P | Site of protein synthesis |
| Q | Powerhouse of the cell |
Identify the correct pair of cellular components.
- P - Ribosomes, Q - Lysosomes
- P - Golgi apparatus, Q - Nucleus
- P - Ribosomes, Q - Mitochondria
- P - Lysosomes, Q - Ribosomes
Answer
P - Ribosomes, Q - Mitochondria.
Reason — Ribosomes are the site of protein synthesis, while mitochondria release energy in the form of ATP and are therefore called the powerhouse of the cell.
During a biology lecture, teacher asked students to identify the types of plastids found in plant cells. The students responded as follows:
Raj - Chloroplasts and Chromoplasts
Sonu - Chromoplasts and Lysosomes
Lata - Chloroplasts and Leucoplasts
Abhay - Leucoplasts and Ribosomes
Who gave the correct answers?
- Raj and Lata
- Sonu and Abhay
- Lata and Abhay
- Raj and Sonu
Answer
Raj and Lata.
Reason — Plastids found in plant cells are of three kinds — chloroplast, chromoplast and leucoplast. Raj and Lata named only plastids, whereas Sonu named lysosomes and Abhay named ribosomes, which are not plastids.
Mohit was studying a plant cell and observed that some green, disc-shaped organelles were responsible for trapping sunlight to produce food. He also noticed another organelle that provided a rigid structure to the cell.
Which organelles was Mohit likely observing?
- Nucleus and Ribosomes
- Mitochondria and Cytoplasm
- Chloroplasts and Cell Wall
- Golgi Apparatus and Cell Membrane
Answer
Chloroplasts and Cell Wall.
Reason — Chloroplasts are the green, disc-shaped organelles that trap solar energy for photosynthesis to produce food, while the cell wall is the rigid layer that provides a definite shape and rigidity to the plant cell.
Name the following:
(i) Cytoplasmic organelle that help in the manufacture of starch.
(ii) The smallest known cell.
(iii) The living component of a cell.
Answer
(i) Leucoplast
(ii) Mycoplasma (PPLO)
(iii) Protoplasm
Give the specific functions of the following cell organelles.
(i) Ribosomes
(ii) Nucleus
(iii) Vacuoles
(iv) Centrosome
Answer
(i) Ribosomes — They are the site of protein synthesis.
(ii) Nucleus — It regulates the growth and reproduction of the cell and transfers hereditary characters from one generation to the next.
(iii) Vacuoles — They give turgidity to the cells and store water and other substances, i.e., food, pigments and waste products.
(iv) Centrosome — It initiates and regulates cell division and forms spindle fibres with the help of asters.
Differentiate between Cell wall and Plasma membrane.
Answer
Differences between Cell wall and Plasma membrane are:
| Cell Wall | Plasma Membrane |
|---|---|
| It is the outermost covering in plant cells. | It is the outermost covering in animal cells and lies next to the cell wall in plant cells. |
| It is a non-living and rigid layer. | It is a flexible, delicate and living membrane. |
| It is freely permeable. | It is selectively permeable. |
| It is made up of cellulose. | It is made up of lipoproteins. |
Differentiate between Ribosomes and Lysosomes.
Answer
Differences between Ribosomes and Lysosomes are:
| Ribosomes | Lysosomes |
|---|---|
| They are the smallest amembranous cell organelles. | They are membranous sacs budded off from the Golgi body. |
| They consist of RNA and associated proteins. | They contain about 40 different types of enzymes. |
| They occur freely in the cytoplasm or remain attached to the rough endoplasmic reticulum. | They lie freely in the cytoplasm. |
| They help in protein synthesis. | They help in intracellular digestion and destroy foreign substances and injured organelles. |
Given below is a structure of animal cell. Match the structures marked (A) to (E) with their correct functions.
Answer
| Label | Organelle | Function |
|---|---|---|
| A | Lysosomes | Breaks down waste materials and foreign substances within the cell. |
| B | Mitochondria | Produces energy in the form of ATP through cellular respiration. |
| C | Ribosomes | Synthesises proteins needed for cell functions. |
| D | Centrosome | Organises microtubules and regulates cell division. |
| E | Nucleus | Controls cell activities and stores genetic information (DNA). |