CG Board Class 9 Science Chapter 6 Solutions: Fundamental Unit of Life: Cell (जीवन की मौलिक इकाई: कोशिका) – 2026-27

Do all the cells appear the same when observed under a microscope?

No, all cells do not appear the same. They show structural variations in shape, size, and internal components depending on their origin and specific functions.

What parts are visible in a cell under a basic light microscope?

Under a standard compound microscope, the prominent visible parts are the cell wall (in plant cells), the cell membrane, the cytoplasm, and a dense dark structure called the nucleus.

What are the similarities between cheek cells and cells in the leaf peel? Write one difference between them.

Both types of cells possess a cell membrane, cytoplasm, and a distinct nucleus.

Leaf peel cells (plant cells) possess a rigid cellulosic cell wall and chloroplasts, whereas cheek cells (animal cells) lack both a cell wall and chloroplasts.

Find out a structure present in plant cells but absent in animal cells.

Cell wall and Plastids (Chloroplasts) are present in plant cells but absent in animal cells.

How does cytoplasm shrink during plasmolysis?

When a plant cell is kept in a hypertonic (concentrated) हल, water moves out of the cell cytoplasm into the surrounding हल due to osmosis. As a result, the cytoplasm along with the cell membrane shrinks away from the rigid cell wall.

What would be the effect on a cell if the cell membrane was not selectively permeable?

If the membrane were not selectively permeable, any harmful or unwanted substance could freely enter the cell, and essential nutrients and internal fluids would leak out uncontrollably. This would disrupt the internal equilibrium (homeostasis) and lead to cell death.

What difference do you see when a deshelled egg is kept in a concentrated sugar हल? What could be the reason for this?

• Observation: The deshelled egg shrinks in size.
• Reason: The concentration of water inside the egg is higher than in the outer concentrated sugar हल. Water leaves the egg through its cell membrane by exosmosis, causing it to shrink.

What is the difference between cell wall and cell membrane?

Can the nucleus be called the control center of the cell? Why?

Yes, the nucleus is called the control center of the cell because it contains genetic material (chromatin/DNA) that directs all metabolic activities, growth, protein synthesis, and cellular reproduction.

Through which cellular organelle can materials be transported from the nuclear membrane to the cell membrane?

Through the Endoplasmic Reticulum (ER), which forms a continuous interconnected network between the nuclear membrane and the cell membrane.

What do you think will be the role of lysosomes in a completely infected cell?

In a completely infected or damaged cell, lysosomes burst open and release their powerful digestive enzymes to digest the entire cell. This prevents the infection from spreading to neighboring healthy cells, which is why lysosomes are termed “suicide bags”.

Why is the chloroplast often called the kitchen of the plant cell?

Chloroplasts contain chlorophyll, which traps solar energy to synthesize food (glucose) from carbon dioxide and water through photosynthesis. Since food for the plant is prepared here, it is called the kitchen of the cell.

Why is it necessary for mitochondria to be present in large numbers inside a cell?

Mitochondria are the sites of cellular respiration where ATP (cellular energy) is generated. Tissues with high metabolic rates (e.g., liver, muscle cells) require a continuous large supply of energy, making high mitochondrial density essential.

As the radius of a spherical cell increases, what difference do you observe in its surface area and volume? How does this affect the surface area to volume ratio?

• As radius (r) increases, surface area increases in square proportion (4π r²), while volume increases much faster in cubic proportion (4/3π r³).
• Consequently, the Surface Area to Volume ratio (SA/V) decreases drastically as the cell grows larger.

What are the advantages for a cell to have a small size?

A small cell size ensures a high surface area to volume ratio, allowing rapid and efficient diffusion of nutrients, gases, and excretory waste across the cell boundary over short internal distances.

(i) Name ‘cell’ was given by one of the following:**

(ii) Cell theory was proposed by:

(iii) Single layered membrane is found in:

(iv) Cellulosic cell wall is not present in one of the following:

(v) Prokaryotic cell has one of these:

• Diagram Description / चित्र विवरण:
• Draw a hexagonal/Cell Wall / कोशिका भित्ति Cell Membrane / कोशिका झिल्ली.
• Vacuole / रसधानी pushing the cytoplasm to the periphery.
• Draw a distinct round केंद्रक placed near the cell margin.
• Scatter oval double-membraned हरितलवक containing stack-like grana in the cytoplasm.

Cell wall is a non-living, rigid, fully permeable outer boundary made of cellulose found only in plant cells. Cell membrane is a living, flexible, selectively permeable boundary made of proteins and lipids found in both plant and animal cells.

• Diagram Description / चित्र विवरण:
• Draw an oval or irregular shape delimited by an outer कोशिका झिल्ली.
• Draw a centrally located round केंद्रक containing chromatin threads and nucleolus.
• Surround the nucleus with अंतःप्रद्रव्यी जालिका and stacked गॉल्जी काय.
• Scatter rod-shaped माइटोकॉन्ड्रिया and small spherical लाइसोसोम in the cytoplasm.

Cell theory established that the cell is the fundamental structural, functional, and organizational unit of all living organisms.

• It disproved the ancient belief of spontaneous generation by establishing that all new cells arise from pre-existing cells through cell division (Omnis cellula-e-cellula).

• Similarities / समानताएं:

1. Both are bounded by a double-layer membrane.
2. Both contain their own genetic material (DNA) and ribosomes, allowing them to divide semi-autonomously.

• Differences / अंतर:

1. Leucoplasts / अवर्णलवक:

• Plant Parts: Underground roots and storage tubers like potato, maize grain, and radish cells.
• Hindi / हिंदी: भूमिगत जड़ें तथा संग्रह तने जैसे आलू, मक्का दाना, तथा मूली की कोशिकाएं।

1. हरितलवक:

• Plant Parts: Green leaves, tender green stems, and unripe green fruits.
• Hindi / हिंदी: हरी पत्तियां, कोमल हरे तने, तथा कच्चे हरे फल।

1. Chromoplasts / वर्णलवक:

• Plant Parts: Petals of flowers, ripe fruits (like tomato, papaya), and seeds.
• Hindi / हिंदी: पुष्पों की पंखुड़ियां, पके हुए फल (जैसे टमाटर, पपीता), तथा बीज।