Cell Structure and Functions Questions & Answers

Hi Everyone!! This article will share Cell Structure and Functions Questions & Answers.

In my previous post, I have shared Cell Structure and Functions Objective Type Questions that includes multiple-choice, true/false, matching, fill-ups, assertion and reason, etc.  So, make sure to check that post as well.

Cell Structure and Functions Questions & Answers

Question 1: Cell is called the structural and functional unit of life. Explain.

Answer: Every living thing is made up of cells and a cell represents the lowest level of organization at which life can exist. Hence, it is called the structural unit of life.
It is the single-cell that performs all the vital functions such as respiration, nutrition, transportation, excretion and reproduction for the whole organism. Hence, it is called the functional unit of life.

Question 2: What does Cell Theory state?

Answer: The Cell Theory states that:
i. All living organisms are made of cells.
ii. In all living things, the cell is the fundamental unit of structure and function.
iii. All cells arise from pre-existing cells.

Must Read: Microorganisms – Friend and Foe Questions & Answers

Question 3: What is a gene?

Answer: A gene is a sequence of nucleotides that expresses a particular trait or a characteristic. It is responsible for the transmission of characteristics from parents to the next generation.

Question 4: Classify cells on the basis of presence or absence of organelles and arrangement of nucleus.

Answer: On the basis of presence or absence of organelles and arrangement of nucleus, cells can be of two types -Prokaryotic cells
Eukaryotic cells

Question 5: Classify organisms on the basis of number of cells present.

Answer: On the basis of number of cells present, organisms can be classified into two types –
Unicellular organisms
Multicellular organisms

Cell Structure and Functions Questions & Answers

Question 6: Give reasons:

(a) The cells found in an organism can come in a variety of different sizes and shapes.
Answer: The cells in an organism can come in a variety of different sizes and shapes to perform a specific function in the body. For example – Amoeba keeps changing its shape to move and engulf food.

(b) The white blood cells are irregular in shape.
Answer:  White blood cells protect us from foreign invaders or pathogens like bacteria, viruses, etc. as they are a part of the immune system. They eliminate pathogens by ‘eating’ them (phagocytosis). WBCs keep circulating in the blood stream but are usually required at the site of infection inside tissues. So, for this to happen, they have to migrate through the walls of small blood vessels and find their way in tissues. This can only occur because they are able to change their shape.

(c) The red blood cells are round and concave.
Answer:  They are round and concave so that they can easily squeeze through the narrow blood capillaries.

(d) The nerve cells are elongated and highly branched.
Answer: The nerve cells are elongated and highly branched because the branches help in the passage of chemical and electrical messages throughout the body.

(e) Spikes are present on the pollen grains.
Answer: This is because, during pollination, the spikes help the pollen grains to stick to the body of the pollinating insect or animal.

Question 7: Why are bacteria classified as prokaryotic organisms?

Answer: Bacteria lack a membrane-bound nucleus and other internal organelles like mitochondria and Golgi bodies. Therefore, they are classified as prokaryotic organisms.

Question 8: Why are vacuoles of animal cells much smaller in comparison to those present in plant cells?

Answer: In animal cells, the vacuole helps in storing various substances such as food, enzymes and waste products for a short period of time. However, in plant cells, its main function is storage and maintaining the structure of the cell. Hence, plant cells have a large centralised vacuole.

Question 9: Why do muscle cells have a larger number of mitochondria compared to other cells of the body?

Answer: Mitochondria are the powerhouse of cells and are chiefly responsible for the synthesis of energy in the form of ATP. The number of mitochondria in a cell depends on how much energy the cell needs to produce. Since, physical activities and movement involve the use of muscles which will require a lot of energy, the number of mitochondria in muscle cells is higher.

Question 10: What would happen if there were no vacuoles in a plant cell?

Answer: Vacuoles are the sites where a cell stores its food and it maintains the structure of the plant cell. So in the absence of vacuoles, the cell won’t be able to store food and maintain its structure, it may not be able to survive.

Cell Structure and Functions Questions & Answers

Question 11: Where are chromosomes found in a cell? State their function.

Answer: They are found in the nucleus of the cell and each chromosome carries genes that are responsible for some trait or characteristic. These genes transfer these characters from the parents to the offspring.

Question 12: A nucleus to a cell is what a brain is to our body. Justify.

Answer: A nucleus controls all the activities of a cell just like a brain does for our body.

Question 13: Why are mitochondria considered as the powerhouse of the cell?

Answer: This is because Mitochondria are responsible for the synthesis of adenosine triphosphate or ATP, the main energy-rich molecule used by the cells.

Question 14: Why are lysosomes known as suicide bags?

Answer: Lysosomes contain substances that help in the digestion of foreign bodies and worn-out cell parts. Hence, when necessary they can digest the entire contents of the cell. In this process, the lysosomes also get destroyed. Hence, lysosomes are called suicidal bags.

Question 15: Write any three main functions of a cell wall.

Answer:
i. Provides shape and rigidity.
ii. Protects the protoplasm.
iii. Involved in the movement of materials in and out.

Question 16: Differentiate between prokaryotic cells and eukaryotic cells based on the following criteria:
i. Size
ii. Chromosome
iii. Membrane bound organelle

Answer:

CriteriaProkaryotic cellsEukaryotic cells
i. SizeSize of cell is generally small.Size of cell is generally large.
ii. ChromosomeIt contains single chromosome.It contains more than one chromosome.
iii. Membrane bound organelle  Membrane bound cell organelles are absent.Membrane bound cell organelles such as mitochondria; plastids, endoplasmic reticulum, etc. are present.

Question 17: Differentiate between plant cells and animal cells.

Answer:

Plant cellsAnimal cells
They are usually larger in size.They are comparatively smaller in size.
They contain a rigid cell wall in addition to cell membrane.They lack cell wall and only show presence of plasma membrane.
These cells show the presence of plastids like chloroplasts.These do not have plastids.
Most of the plant cells show presence of single large vacuole.A single large vacuole is absent in animal cells however, they often show presence of many small vacuoles.
Centrioles and centrosomes are absent.Centrioles and centrosomes are present.

Question 18: What is Cytoplasmic streaming? Give its importance.

Answer: The movement of the fluid part of the cytoplasm within a cell is known as cytoplasmic streaming. It helps in the transportation of proteins, nutrients and organelles within the cell.

Question 19: Write a short note on:

(a) Golgi Bodies
Found located near the nucleus, Golgi bodies modify the proteins made by the ribosomes. They also help in transporting them to various organelles and plasma membrane.

(b) Ribosomes
Made up of ribosomal RNA and ribosomal proteins, these are small round particles that are found either attached to the surface of the endoplasmic reticulum or scattered in the cytoplasm. They are associated with protein synthesis.

(c) Centrioles and Centrosomes
Present only in animal cells, they play an important role in cell division.

(d) Plasma Membrane
It is a flexible boundary of a cell that separates a cell from its surroundings. It is responsible for the shape of the cell. Made up of proteins and lipids, the plasma membrane is porous in nature and allows the movement of substances, both inward and outward. However, it is semi-permeable and the movement of substance is highly regulated. Only some molecules can pass through it. Other molecules are only admitted at certain times and in limited amounts. Others are not allowed in at all. So, a plasma membrane helps in maintaining the integrity of the cell.

So, these were Cell Structure and Functions Questions & Answers.