CG Board Class 8 Science Chapter 7 Solutions: Structural and Functional Unit of Our Body – The Cell (शरीर की संरचनात्मक एवं कार्यात्मक इकाई – कोशिका) – 2026-27

The shape of an onion peel cell is generally rectangular.

Yes, a cell has a definite margin formed by the plasma membrane and cell wall.

Yes, a sticky fluid substance called protoplasm (cytoplasm and nucleoplasm) is filled inside the cell.

Yes, there is a round or oval structure inside the cell called the nucleus.

The outer layer of a plant cell present outside the plasma membrane is called the Cell Wall (made of cellulose).

The main function of Golgi bodies (Golgi apparatus) is to secrete various chemical products inside the cell.

Chromoplast** (coloured plastid) is found in a red apple.

Ribosome** is known as the ‘protein factory’ of the cell because it produces proteins.

Mitochondria** is known as the ‘Power house’ of the cell because here energy is produced by the oxidation of food products during respiration.

The Nucleus is called the ‘control room’ of the cell because all life processes and cellular activities are controlled from here.

Chromosomes are made of DNA (Deoxyribonucleic Acid) and proteins (formed by the shrinking of chromatin network during cell division).

1. It controls all vital life processes and metabolic activities of the cell.
2. It contains chromosomes/DNA which carry genetic material and transfer hereditary traits from parents to offspring.
3. The nucleolus inside the nucleus helps in cell division.

(Page 78 of Textbook)

• English Comparison:

1. Nucleus Structure: Eukaryotic cells have a well-defined nucleus with a clear nuclear membrane. Prokaryotic cells lack a nuclear membrane and a well-defined nucleus.
2. Cell Organelles: Eukaryotic cells contain membrane-bound organelles like mitochondria, Golgi apparatus, and endoplasmic reticulum. Prokaryotic cells lack these main cell organelles.
3. Examples: Eukaryotics include Amoeba, plants, animals, and humans. Prokaryotics include Bacteria and Cyanobacteria (blue-green algae).

• Hindi Comparison:

1. केंद्रक संरचना: यूकेरियोटिक कोशिका में सुव्यवस्थित केंद्रक तथा स्पष्ट केंद्रक झिल्ली पाई जाती है। प्रोकेरियोटिक कोशिका में केंद्रक झिल्ली तथा सुस्पष्ट केंद्रक का अभाव होता है।
2. कोशिका अंगक: यूकेरियोटिक कोशिका में माइटोकॉन्ड्रिया, गॉल्जीकाय, अंतः प्रद्रव्यी जालिका आदि अंगक उपस्थित होते हैं। प्रोकेरियोटिक कोशिका में ये प्रमुख अंगक अनुपस्थित होते हैं।
3. उदाहरण: यूकेरियोटिक के उदाहरण अमीबा, पौधे, जंतु तथा मनुष्य हैं। प्रोकेरियोटिक के उदाहरण जीवाणु (Bacteria) तथा नील हरित शैवाल (Cyanobacteria) हैं।

(1) Cell wall of plant cell is made of:**

(c) सेल्यूलोज

(2) The power house of the cell is:

(a) Centrosome

(b) Ribosome

(c) Nucleus

(d) Mitochondria

(d) माइटोकॉन्ड्रिया

(3) Protein synthesis in the cell is done by:

(a) Ribosome

(b) Plastids

(c) Vacuoles

(d) Nucleus

(a) राइबोसोम

(4) Example of Prokaryotic cells is:

(a) Euglena

(b) Amoeba

(c) Paramoecium

(d) Blue green algae

(d) नील हरित शैवाल

(5) Nuclear membrane is not present in:

(a) Onion cells

(b) Bacterial cells

(c) Inner cheek cells

(d) Hydra cells

(b) जीवाणु कोशिका

A cell is called the functional unit of life because in single-celled organisms (like Amoeba and Paramecium), all vital life functions such as nutrition, respiration, excretion, and reproduction are carried out within a single cell. In multicellular organisms, cells group together to perform specialized functions that keep the body alive.

The main functions of the plasma membrane are:

1. It helps in maintaining the shape of the cell.
2. Being semi-permeable, it controls the movement of molecules into and out of the cell.
3. It protects and provides support to the inner contents of the cell.

In a plant cell, the outer protective structure present outside the plasma membrane is called the Cell Wall. It is non-living and made of cellulose.

• English:
• Hindi:

Chloroplasts contain green chlorophyll pigments. Their main function is to carry out photosynthesis, preparing food for plants using sunlight, water, and carbon dioxide.

Plant Cell Diagram Structure:** It has an outer rigid cell wall, followed by plasma membrane, large central vacuole, green chloroplasts, dictyosomes (Golgi bodies), mitochondria, cytoplasm, endoplasmic reticulum, and a prominent nucleus.

• Animal Cell Diagram Structure: It has an outer flexible plasma membrane (no cell wall), small vacuoles, centrosome with centrioles near the nucleus, disc-shaped Golgi apparatus, mitochondria, cytoplasm, endoplasmic reticulum, and a rounded central nucleus.

Cells are of different shapes and sizes because they are specialized to perform different functions in living organisms. For example:

1. Nerve cells are long and branched to transmit messages over long distances.
2. Muscle cells are elongated/spindle-shaped to contract and relax for body movement.
3. Amoeba changes its shape continuously for movement and capturing food.