GSEB Class 8 Science Solutions Chapter 8 Cell Structure and Functions

Question 1. Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body.
(b) Muscle cells are branched.
(c) The basic living unit of an organism is an organ.
(d) Amoeba has irregular shape.
Answer:
(a) True
(b) True
(c) False
(d) True.
In simple words: This question checks whether you know the basic facts about cells and organisms. Unicellular means one cell, so (a) is correct. Muscle cells are typically spindle-shaped, not branched, so (b) is incorrect. The basic unit of life is a cell, not an organ, making (c) false. Amoeba is known for its constantly changing shape, so (d) is also correct.

Exam Tip: Remember key definitions: 'unicellular' means having one cell, 'multicellular' means having many cells. The cell is the fundamental unit of all living organisms.

Question 2. Make a sketch of the human nerve cell. What function do nerve cells perform?
Answer:
Nerve cells help in the transfer of messages from various body parts to the brain and from the brain to various parts of the body. They also help in the coordination of the functions of the body's organs.
In simple words: Nerve cells, also called neurons, carry signals around your body. They send messages from your body parts to your brain, and from your brain back to your body, helping everything work together smoothly.

Exam Tip: When drawing a nerve cell, make sure to clearly label the cell body, nucleus, dendrites, axon, and nerve endings. For functions, focus on message transmission and coordination.

Question 3. Write short notes on the following:
(a) Cytoplasm
(b) Nucleus of a cell.
Answer:
(a) Cytoplasm: It is a jelly-like substance that is present between the nucleus and the cell membrane. Various other organelles are present in the cytoplasm. It is made up of carbohydrates, proteins, and water.
(b) Nucleus of a Cell: The nucleus is a spherical, dense structure commonly situated in the center of the cell. A nuclear membrane separates the nucleus from the cytoplasm. It contains genetic materials like RNA and DNA. The nuclear membrane allows the transfer of materials into the nucleus and cytoplasm. It also contains thread-like structures called chromosomes, which are genetic material. The nucleus controls the various functions of the cell.
In simple words: (a) Cytoplasm is the clear, jelly-like filling inside a cell, but outside the nucleus. It holds all the cell's tiny parts and is mostly water, proteins, and carbs. (b) The nucleus is like the cell's brain, usually found in the middle. It's a dense, round part with its own membrane and contains all the genetic information that controls how the cell works and grows.

Exam Tip: For short notes, define the term, mention its location within the cell, and describe its key components and functions. Use simple, clear language.

Question 4. Which part of the cell contains organelles?
Answer: Cytoplasm.
In simple words: The cytoplasm is the part of the cell that holds all the small working parts, called organelles.

Exam Tip: Remember that organelles are the "mini-organs" of the cell, and they are suspended within the cytoplasm, not the nucleus.

Question 5. Make sketches of animal and plant cell. state the differences between them.
Answer:
Differences:
Plant Cell:

• A cell wall is present.
• Chloroplast is present.
• It has no centrosome.
• Vacuoles are large or may be single and large, as in an onion cell.

• A cell wall is absent.
• Chloroplast is absent.
• A centrosome is present near the nucleus.
• Vacuoles are much smaller, as in cheek cells.

Exam Tip: When sketching, use simple, clear outlines and label the key distinguishing features. For differences, create a table or use bullet points to clearly compare each characteristic side-by-side.

Question 6. State the difference between eukaryotes and prokaryotes.
Answer: Eukaryotes have a well-designed nucleus and organelles covered with membranes, while prokaryotes do not have a well-designed nuclear membrane.
In simple words: Eukaryotes are cells with a proper nucleus and other parts wrapped in membranes. Prokaryotes are simpler cells that do not have a nucleus or other parts enclosed by membranes.

Exam Tip: The main distinction is the presence or absence of a membrane-bound nucleus and other organelles. Eukaryotes (like plant and animal cells) have them, prokaryotes (like bacteria) do not.

Question 7. Where are chromosomes found in a cell? State their function.
Answer: Chromosomes are situated in the nucleus of a cell. They carry the characteristics of parent cells to the daughter cells.
In simple words: Chromosomes are located inside the cell's nucleus. Their job is to carry genetic information, like instructions, from parents to their offspring.

Exam Tip: Always remember that chromosomes are the carriers of hereditary information, ensuring traits are passed down through generations.

Question 8. 'Cells are the basic structural units of living organisms'. Explain.
Answer: Many cell units form many tissues, and tissues then form an organ. The organs combine to form a complete body. In this way, the cell is the structural unit of an organism. Cells perform all the basic functions of an organism. So, they are also functional units of living beings.
In simple words: Cells are like the building blocks of all living things. Many cells group together to make tissues, then tissues make organs, and organs come together to form an entire body. Cells also do all the important jobs that keep an organism alive.

Exam Tip: When explaining the cell as a basic unit, remember both its structural role (forming tissues, organs, systems) and its functional role (carrying out life processes).

Question 9. Explain why chloroplasts are found only in plant cells.
Answer: Photosynthesis is the main process in plants. Photosynthesis takes place in the presence of chlorophyll, which is found in chloroplasts. So, chloroplasts are found only in plant cells.
In simple words: Chloroplasts are only in plant cells because they contain chlorophyll, which is needed for photosynthesis. Photosynthesis is how plants make their own food using sunlight, a process that animals don't do.

Exam Tip: Connect chloroplasts directly to their unique function: photosynthesis, which is exclusive to plants and some other autotrophs.

Question 10. Complete the crossword with the help of clues given below.
Across:
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down:
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
Answer:

Exam Tip: Crosswords are a good way to reinforce vocabulary. Pay attention to clue wording and letter intersections to find the correct terms related to cells and their parts.