NEET Biology Cell The Unit of Life Important Questions Set 02

These Class 11 NEET Biology important questions on Cell : The Unit of Life give 23 questions with step-by-step answers, arranged as very short, short and long answer types, taken from a model test paper. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. Who gave the statement Omnis cellula e cellula? What does it mean?
Answer: Rudolf Virchow. It means all cells arise from pre-existing cells.

Question 2. What is a nucleoid?
Answer: The region where the genetic material is present in a prokaryotic cell is called nucleoid.

Question 3. Define gram negative bacteria.
Answer: Bacteria that do not take up the Gram stain are called Gram negative bacteria.

Question 4. Which membrane protein is involved in facilitated diffusion?
Answer: Carrier protein

Question 5. Which cell organelle synthesises the enzymes of lysosomes?
Answer: RER

Question 6. What are stroma lamellae?
Answer: The thylakoids of different grana are connected by flat membranous tubules called the stroma lamellae.

Question 7. Mention the two subunits of ribosome of eukaryotic cell.
Answer: 60S and 40S

Question 8. Which type of arrangement of fibrils is found in centrioles?
Answer: 9 + 0

Short Answer Type Questions

Question 9. Write two postulates of the cell theory.

Answer:

(i) All living organisms are composed of cells and their products.

(ii) All cells arise from pre-existing cells.

Question 10. What are plasmids? Where are they present?

Answer:

Plasmids are extra-chromosomal or extra-nuclear segments of circular DNA present in the cytoplasm of bacterial cells.

The pasmid DNA confers certain unique phenotypic characters to such bacteria. One such character is resistance to antibiotics.

Question 11. How chromosomes are formed from chromatin?
Answer: Chromatin is composed of DNA, RNA histone and nonhistone protein. Chromosome are formed by condensation i.e. coiling and supercoiling of chromatin.

Question 12. Why are mitochondria known as semi-autonomous organelles?
Answer: Mitochondria are capable of making some of their own proteins as they contain their own ribosomes. However, they require few proteins from the cytoplasm which are formed under the influence of nucleus. Thus, functioning of mitochondria is partly controlled by themselves and partly by nucleus of the cell and availability of materials from cytoplasm. Hence, they are known as semi-autonomous organelles.

Question 13. 'X' is a type of cell organelle found in plant cells. One of its type 'Y' gets converted into another type 'Z' that provides colour to plant products like fruits. Identify X, Y and Z. Give one common feature of 'X' and mitochondria.

Answer:

(a) X–Plastid

Y–Chloroplast

Z–Chromoplast

(b) Both are double membrane-bound organelles.

Question 14. Which type of proteins are formed by free and attached ribosomes?
Answer: Free ribosomes synthesise structural and enzymatic proteins for use inside the cell. The attached ribosomes synthesise proteins for transport.

Question 15. What are secondary constrictions and satellite chromosomes?
Answer: A few chromosomes may have additional constrictions termed as secondary constrictions near their ends. The part of the chromosome beyond the secondary constriction is called satellite. The secondary constrictions are always constant in their positions and the chromosomes having secondary constrictions are known as satellite or SAT chromosomes.

Short Answer Type Questions

Question 16. Explain the terms related to a prokaryotic cell
(a) Mesosomes
(b) Chromatophores

Answer:

Mesosomes : Mesosome is a special membranous structure formed by the extensions of plasma membrane into the cell. They are mainly associated with respiration, secretion processes, storage of enzymes, replication during cell division and increase in the surface area of the plasma membrane.

Chromatophores : In some prokaryotes like cyanobacteria, there are other membranous extensions into the cytoplasm called chromatophores which contain pigments.

Question 17. Draw a well-labelled diagram of ER showing its types.
Answer: A well-labelled diagram should show these parts: Nucleus; Nuclear pore; Rough endoplasmic reticulum; Ribosome; Smooth Endoplasmic reticulum.

Question 18. Write the chemical composition of cell wall of
(a) Bacteria
(b) Fungus
(c) Alga

Answer:

1. Bacterial cell wall : The bacterial cell wall consists of peptidoglycan which contains polymers of modified sugars (N-acetyl glucosamine and N-acetyl muramic acid), cross-linked by short peptides.

2. Fungal cell wall : The fungal cell wall is generally composed of chitin, a polymer of acetylglucosamine units.

3. Algal cell wall : The algal cell wall is made up of cellulose, galactans, mannans and minerals like calcium carbonate.

Question 19. Explain the structure of protein factories.
Answer: (i) Ribosomes are membraneless granular structures present in the cytoplasm.
(ii) Each ribosome is made up of two subunits – a large and a small subunit. A 70S ribosome is made up of 50S, large subunit and 30S, small subunit. A 80S ribosome is made up of 60S, large subunit and 40S, small subunit.
(iii) Chemically each ribosome is made up of ribonucleic acid (rRNA) and protein.

Question 20. Give three differences between cilia and flagella.
Answer: Cilia Flagella
1. The number of cilia per cell is usually very large 1. The number of flagella per cell is (300–14000). usually 1–4.
2. They are smaller in size. 2. They are longer in size.
3. Cilia usually occur throughout or major part of 3. Flagella are commonly found at one the surface of a cell end of the cell.
4. Cilia help in locomotion, feeding, circulation etc. 4. Flagella help in locomotion.

Question 21. (a) What is the composition of chromatin?
(b) What is the function of histone proteins?
Answer: (a) Chromatin contains DNA and some basic proteins called histones, some non-histone proteins and also RNA.
(b) The histone proteins are the packaging proteins that are associated with packaging of DNA into compact structure called chromosomes.

Long Answer Type Questions

Question 22. Differentiate between prokaryotic and eukaryotic cells on the basis of
(a) Nucleus
(b) Membrane-bound organelles
(c) Nucleolus
(d) Ribosomes
(e) Plasmids Prokaryotic cell Eukaryotic cell

Answer:

Question 23. (i) Draw a well-labelled diagram of T.S. of centriole.
(ii) Give the functions of centriole.

Answer:

A well-labelled diagram should show these parts: Massule pericentriolar; (i) satelliteor; C-A Connective; Triplet fibril; Cart-Wheel; Structure; Central rod (HUB); 9 Spokes; .

(ii) The centrioles form the basal body of the cilia and flagella and spindle fibres that give rise to spindle apparatus during cell division in animal cells.