Samacheer Kalvi Class 6 Science Solutions Term 2 Chapter 5 The Cell

Samacheer Kalvi 6th Science The Cell Text Book Back Questions and Answers

I. Choose the correct answer:

 

Question 1. The unit of measurement used for expressing dimension (size) of cell is
(a) centimeter
(b) millimeter
(c) micrometer
(d) meter
Answer: (c) micrometer
In simple words: Cells are very small, so we use a unit called a micrometer to measure their size. This helps in describing their tiny dimensions accurately.

🎯 Exam Tip: Remember that a micrometer is \(10^{-6}\) meters, highlighting the microscopic nature of cells.

 

Question 2. Under the microscope, Priya observes a cell that has a cell wall and a distinct nucleus. The cell that she observed is
(a) a plant cell
(b) an animal cell
(c) a nerve cell
(d) a bacteria cell
Answer: (a) a plant cell
In simple words: Priya saw a plant cell. Plant cells have a strong cell wall and a clear control center called a nucleus, which are key features.

🎯 Exam Tip: The presence of both a cell wall and a distinct nucleus is the defining characteristic of a plant cell; bacterial cells lack a distinct nucleus.

 

Question 3. A 'control centre' of the eukaryotic cell is
(a) Cell wall
(b) Nucleus
(c) Vacuoles
(d) Chloroplast
Answer: (b) Nucleus
In simple words: The nucleus is like the brain of a cell. It holds the cell's genetic information and directs all its activities.

🎯 Exam Tip: Always remember the nucleus as the "brain" or "control center" of the cell, as it regulates gene expression and cell division.

 

Question 4. Which one of the following is not a unicellular organism?
(b) Amoeba
(c) Spirogyra
(d) Bacteria
Answer: (c) Spirogyra
In simple words: Spirogyra is not a single-celled organism. It grows in long strings made of many cells joined together.

🎯 Exam Tip: While some algae can be unicellular, Spirogyra typically forms multicellular filaments, making it different from truly unicellular organisms like Amoeba or Bacteria.

 

Question 5. Most organelles in a eukaryotic cell are found in the
(a) Cell wall
(b) cytoplasm
(c) nucleus
(d) Vacuole
Answer: (b) cytoplasm
In simple words: Most cell parts are found floating in the cytoplasm. This is the jelly-like liquid that fills the cell and supports everything inside.

🎯 Exam Tip: Visualise the cytoplasm as the cell's "internal ocean" where all organelles are suspended and metabolic activities occur.

II. Fill in the Blanks

 

Question 1. The instrument used to observe the cell is ...........
Answer: The microscope is the instrument used to observe cells because they are too small to be seen with the naked eye. This tool magnifies their tiny structures.
In simple words: We use a microscope to see cells.

🎯 Exam Tip: Mentioning both "microscope" and "magnification" shows a complete understanding of how cells are viewed.

 

Question 2. I control the food production of a cell. Who am I? ...........
Answer: The chloroplast is the organelle that controls food production in a plant cell, using sunlight. It is the site of photosynthesis.
In simple words: Chloroplasts make food for the cell.

🎯 Exam Tip: Associate "chloroplast" directly with "photosynthesis" and "food production" in plant cells.

 

Question 3. I am like a policeman. Who am I .........?
Answer: The cell membrane acts like a policeman, controlling what enters and leaves the cell. It ensures only necessary substances pass through.
In simple words: The cell membrane controls what goes in and out.

🎯 Exam Tip: The cell membrane's function is selective permeability – it chooses what can enter or exit the cell.

 

Question 4. The Term "cell" was coined by ...........
Answer: Robert Hooke coined the term "cell" after observing cork slices under a microscope. His observation of small, box-like structures led to this naming.
In simple words: Robert Hooke named the "cell".

🎯 Exam Tip: Robert Hooke's contribution in 1665 is a key historical fact in cell biology.

 

Question 5. The egg of an Ostrich is the ........... single cell.
Answer: The egg of an Ostrich is the largest single cell known. Its remarkable size makes it visible without a microscope.
In simple words: An Ostrich egg is the biggest single cell.

🎯 Exam Tip: Highlighting the ostrich egg as the largest single cell helps students grasp the concept of cell size variation.

III. True or False

 

Question 1. A cell is the smallest unit of life.
Answer: True
In simple words: True. Cells are the smallest living parts that can do all life jobs.

🎯 Exam Tip: This statement is a fundamental principle of the cell theory, highlighting the cell as the basic unit of all organisms.

 

Question 2. Nerve cell is the longest cell
Answer: True
In simple words: True. Nerve cells, or neurons, can be very long to send signals over distances.

🎯 Exam Tip: Emphasise that the length of nerve cells is crucial for efficient communication across the body.

 

Question 3. Prokaryotes were the first form of life on earth.
Answer: True
In simple words: True. The earliest and simplest living things on Earth were prokaryotes, like bacteria.

🎯 Exam Tip: Understanding the order of appearance of cell types (prokaryotes first, then eukaryotes) is important for evolutionary biology.

 

Question 4. The organelles of both plants and animals are made up of cells. (Organelles – Found inside the cell)
Answer: False
In simple words: False. Organelles are tiny parts *inside* cells, not cells themselves. Cells are made of organelles, not the other way around.

🎯 Exam Tip: Clarify that organelles are components *within* a cell, performing specific tasks, while the cell itself is the fundamental unit.

 

Question 5. New cells are produced from existing cells.
Answer: True
In simple words: True. New cells are always made from cells that already exist, by dividing.

🎯 Exam Tip: This is another core tenet of the cell theory: "Omnis cellula e cellula," meaning all cells arise from pre-existing cells.

IV. Match the following

 

Question. Match the following.
Answer:

In simple words: The nucleus is the control center. Chloroplasts make food in plants. The nuclear membrane guards the nucleus. The cell membrane controls the whole cell. Mitochondria make energy.

🎯 Exam Tip: Carefully learn the function of each organelle and its common name to match them correctly.

V. Arrange in a correct sequence

 

Question 1. Arrange the following in a correct sequence: Elephant, Cow, Bacteria, Mango, Rose plant.
Answer: The correct sequence, arranged by size from smallest to largest, is: Bacteria, Mango, Rose plant, Cow, Elephant. This order highlights the vast size differences among living organisms.
In simple words: Smallest to biggest, the order is Bacteria, Mango, Rose plant, Cow, then Elephant.

🎯 Exam Tip: Pay attention to the instruction (e.g., smallest to largest) and consider all items when determining the sequence.

 

Question 2. Arrange the following in a correct sequence: Hen Egg, Ostrich egg, Insect egg.
Answer: Arranging these eggs from smallest to largest gives the sequence: Insect egg, Hen egg, Ostrich egg. This demonstrates the size variation even among different types of eggs, which are all single cells.
In simple words: From smallest to largest, the eggs are: Insect egg, then Hen egg, then Ostrich egg.

🎯 Exam Tip: Remember that even a large ostrich egg is a single cell, showcasing the incredible range of cell sizes.

VI. Analogy

 

Question 1. Prokaryote: Bacteria :: Eukaryote :
Answer: The analogy is: Prokaryote is to Bacteria as Eukaryote is to Plants, Animals. Prokaryotes are simple cells like bacteria, while eukaryotes are complex cells found in plants and animals.
In simple words: Prokaryotes are like bacteria. Eukaryotes are like plants and animals.

🎯 Exam Tip: Understand the key differences between prokaryotic and eukaryotic cells, especially the presence of a true nucleus in eukaryotes.

 

Question 2. Spirogyra: Plant cell :: Amoeba :
Answer: Spirogyra is a type of plant cell (alga), similar to how Amoeba represents an animal cell. Both are often used as examples for their respective cell types.
In simple words: Spirogyra is a plant cell. Amoeba is an animal cell.

🎯 Exam Tip: Recognize common examples of both plant and animal cells, even single-celled ones like Amoeba.

 

Question 3. Food producer : Chloroplasts :: Power house :
Answer: Chloroplasts are the food producers of a cell, just as Mitochondria are the powerhouses. Chloroplasts use light to make food, and mitochondria generate energy for cell activities.
In simple words: Chloroplasts make food. Mitochondria make energy.

🎯 Exam Tip: Always link chloroplasts to photosynthesis and mitochondria to cellular respiration (energy production).

VII. Give a Very short answer:

 

Question 1. Who discovered the cell in 1665?
Answer: The English scientist Robert Hooke discovered the cell in the year 1665. He observed small, box-like structures in cork slices using his microscope and named them "cells".
In simple words: Robert Hooke, an English scientist, found cells in 1665.

🎯 Exam Tip: Remembering the name of the discoverer and the year is crucial for historical context in biology.

 

Question 2. What type of cells do we have?
Answer: Humans, and all complex organisms, have eukaryotic cells. These cells are characterized by having a distinct nucleus and other membrane-bound organelles that perform specific functions.
In simple words: Humans have eukaryotic cells. These cells have a clear nucleus and other small parts inside.

🎯 Exam Tip: Differentiate between prokaryotic and eukaryotic cells based on the presence of a membrane-bound nucleus and organelles.

 

Question 3. What are the essential components of a cell?
Answer: A typical cell has three main parts: an outer cell membrane, which controls what goes in and out; a liquid cytoplasm, which fills the cell and holds organelles; and a nucleus, which is the control center. These three components are crucial for cell function.
In simple words: A cell has three main parts: cell membrane (outside cover), cytoplasm (jelly inside), and nucleus (control center).

🎯 Exam Tip: These three components (cell membrane, cytoplasm, nucleus) are universally present in most cells and are essential to life.

 

Question 4. What are the organelles found only in plant cells?
Answer: Two important organelles found only in plant cells are the cell wall and chloroplasts. The cell wall provides rigid support and protection, while chloroplasts carry out photosynthesis to make food using sunlight.
In simple words: Only plant cells have a cell wall and chloroplasts.

🎯 Exam Tip: Focus on the unique structures that differentiate plant cells from animal cells, particularly those involved in photosynthesis and structural support.

 

Question 5. Give any two examples of eukaryotic cells.
Answer: Two examples of eukaryotic cells include plant cells and animal cells. These cells are more complex, possessing a true nucleus and various membrane-bound organelles.
In simple words: Plant cells and animal cells are examples of eukaryotic cells.

🎯 Exam Tip: Remember that all multicellular organisms, including plants and animals, are made of eukaryotic cells.

VIII. Give a short answer:

 

Question 1. Why cells are called building blocks of life?
Answer: Cells are called the building blocks of life because, just like bricks make a wall, cells are the fundamental structural and functional units that make up all living organisms. They perform all the necessary life processes, from growth to reproduction.
In simple words: Cells are like tiny bricks that build all living things. They do everything needed for life, so they are called building blocks.

🎯 Exam Tip: Use the "bricks of a wall" analogy to clearly explain why cells are considered the basic units of life.

 

Question 2. Identify any four parts of the plant cell?
Answer: Four important parts of a plant cell are: 1. **Cell Wall:** A rigid outer layer that provides support and protection. 2. **Cell Membrane:** Controls what substances enter and leave the cell. 3. **Nucleus:** Contains the genetic material and controls cell activities. 4. **Chloroplasts:** Sites of photosynthesis, where food is made using sunlight. These parts work together to allow the plant cell to function and thrive.
In simple words: Four parts of a plant cell are: cell wall, cell membrane, nucleus, and chloroplasts.

🎯 Exam Tip: When listing parts, always include a brief description of their function to show comprehensive knowledge.

 

Question 3. Distinguish between prokaryotic and eukaryotic cells
Answer:

Prokaryotic cells are generally smaller, ranging from 1 to 2 micrometers in diameter, while eukaryotic cells are larger, from 10 to 100 micrometers. Prokaryotic cells lack membrane-bound organelles, which are present in eukaryotic cells. Furthermore, prokaryotes do not have a true nucleus (their genetic material is free in the cytoplasm), whereas eukaryotes possess a distinct nucleus with a nuclear membrane and nucleolus. These differences highlight the evolutionary complexity of eukaryotic cells.
In simple words: Prokaryotic cells are small and simple, with no clear nucleus or other tiny parts inside. Eukaryotic cells are bigger and complex, with a clear nucleus and many tiny parts.

🎯 Exam Tip: When distinguishing, always mention the presence/absence of a nucleus, membrane-bound organelles, and relative size as key points.

 

Question 4. Identify the parts of the plant cell labeled A, B, C, D in the diagram.
Answer:The diagram shows a plant cell with different parts labeled. A represents the Cell Wall, which provides structural support. B is the Cytoplasm, the jelly-like substance filling the cell. C points to the Nucleus, the cell's control center. D indicates the Mitochondria, which are responsible for generating energy for the cell. This diagram illustrates the key components of a plant cell.
In simple words: In the plant cell picture, A is the Cell Wall, B is the Cytoplasm, C is the Nucleus, and D is the Mitochondria.

🎯 Exam Tip: Knowing the location and function of key organelles in a plant cell diagram is fundamental for understanding cell biology.

 

Question 5. Write about the contribution of Robert Hooke in cell biology
Answer: Robert Hooke, a scientist and inventor, significantly contributed to cell biology by improving the microscope and building his own compound microscope. In 1665, he observed thin slices of cork and saw many tiny, hexagonal, box-like spaces, which he named "cells." These observations were published in his book, "Micrographia," where he first used the term "Cell" to describe these basic units of tissue. His work laid the foundation for the study of cells.
In simple words: Robert Hooke was a scientist who made microscopes better. In 1665, he looked at cork and saw tiny boxes, which he called "cells." He wrote about this in his book "Micrographia," and this started the study of cells.

🎯 Exam Tip: Focus on Hooke's key achievements: improving the microscope, observing cork cells, coining the term "cell," and publishing "Micrographia."

IX. Answer in detail:

 

Question 1. Tabulate any five cell organelles and their function.
Answer:

The table above outlines five key cell organelles along with their main functions and special names. The cell wall protects the cell; the cell membrane acts as a "gate," controlling what enters and leaves. The cytoplasm is the watery gel where cell parts move, often called the "area of movement." The nucleus, known as the "control center," regulates all cell activities. Finally, mitochondria, the "powerhouses" of the cell, produce and supply energy.
In simple words: The table shows five cell parts: cell wall (protects), cell membrane (controls entry), cytoplasm (jelly for movement), nucleus (brain), and mitochondria (energy maker). Each part helps the cell work.

🎯 Exam Tip: When tabulating, ensure clarity with distinct columns for name, function, and any special terms associated with the organelle.

 

Question 2. Draw a neat labelled diagram of a prokaryotic cell
Answer:Students should draw a prokaryotic cell, showing its key structures. The diagram should include the flagella for movement, pili for attachment, a cell wall for protection, and a cell membrane beneath it. Inside, the cytoplasm contains ribosomes and an incipient nucleus (nucleoid region) where genetic material is located, but without a true nuclear membrane. Some prokaryotes also have mesosomes, which are inward foldings of the cell membrane. This detailed drawing helps visualize the simplicity of prokaryotic cell structure.
In simple words: Draw a simple cell like a bacteria. Label its parts: flagella (tail), cell wall, cell membrane, cytoplasm, and the area with its DNA (nucleoid).

🎯 Exam Tip: For diagrams, accuracy in labeling and proportionality of parts are crucial for scoring full marks.

X. Project (For Students)

 

Question 1. Use your imagination and create a 3-D model of a plant cell?
Answer: For this project, students are encouraged to create a three-dimensional model of a plant cell using various materials. The model should accurately represent key organelles like the cell wall, cell membrane, nucleus, chloroplasts, and a large central vacuole, showcasing their relative sizes and positions within the cell. This hands-on activity helps in understanding cell structure.
In simple words: Make a 3D model of a plant cell. Show its parts like the cell wall, nucleus, and chloroplasts.

🎯 Exam Tip: Focus on accurately representing the key organelles and their relative positions within the cell for a successful model.

 

Question 2. Explain how to use food materials to make a cell body and organelles for a 3-D model.
Answer: To build the plant cell model, use different food items: jelly or cake can form the cell body (cytoplasm), while nuts and dry fruits can represent the various cell organelles. Once complete, display the model in the classroom to explain the cell structure and invite questions from teachers and other students, fostering interactive learning. This creative approach makes learning about cells fun and engaging.
In simple words: Use food items like jelly for the cell body and nuts for cell parts to make your model. Show it in class and explain how it works.

🎯 Exam Tip: Creativity and clear representation of cell structures using everyday materials are key for an engaging project.

Samacheer Kalvi 6th Science The Cell Additional Important Questions and Answers

I. Choose the right answer:

 

Question 1. The first cell formed in the earth
(a) Eukaryotic cell
(b) Algal cell
(c) Fungal cell
(d) Prokaryotic cell
Answer: (d) Prokaryotic cell
In simple words: The first cells on Earth were simple prokaryotic cells, like early bacteria.

🎯 Exam Tip: Remember that prokaryotes are simpler and evolved before the more complex eukaryotic cells.

 

Question 2. Robert Hooke published a book named _______ in the year 1665.
(a) Cellula
(b) Micrographia
(c) Cell biology
(d) Organelles
Answer: (b) Micrographia
In simple words: Robert Hooke wrote a book called Micrographia in 1665, describing his cell observations.

🎯 Exam Tip: Knowing the title of Robert Hooke's seminal work is important for the history of cell biology.

 

Question 3. The pigment present in leaf to absorb light is
(a) chlorophyll
(b) chloroplast
(c) chromoplast
(d) leucoplast
Answer: (a) chlorophyll
In simple words: Chlorophyll is the green color in leaves. It helps plants catch sunlight to make food.

🎯 Exam Tip: Distinguish between chlorophyll (the pigment) and chloroplast (the organelle where photosynthesis occurs).

 

Question 4. The largest cell is the egg of an _______ with 170-millimeter width.
(a) Ostrich
(b) viper
(c) tortoise
(d) Hen
Answer: (a) Ostrich
In simple words: The biggest single cell in the world is an Ostrich egg, which is about 170 millimeters wide.

🎯 Exam Tip: The Ostrich egg is a classic example used to illustrate the largest single cell, often surprising students with its size.

II. Assertion and Reason

 

Question 1. Assertion (A) : Chloroplast is a cell organelle Reason (R) : An organelle is a distinct part of the cell which has a particular structure and Function.
(a) Assertion (A) and Reason R - True and R is the correct explanation of A
(b) Both A and R - true but R is not the correct explanation of A
(c) A True but R False
Answer: (a) Assertion (A) and Reason R - True and R is the correct explanation of A
In simple words: Both statements are true. The reason correctly tells us why a chloroplast is called an organelle, as it's a distinct part with its own job.

🎯 Exam Tip: For Assertion-Reason questions, first check if both statements are true individually, then evaluate if the Reason correctly explains the Assertion.

 

Question 2. Assertion (A) : Mitochondria is an important organ cell of the cell Reason (R) : Mitochondria is involved in food preparation
(a) Assertion (A) and Reason R - True and R is the correct explanation of A
(b) Both A and R - true but R is not the correct explanation of A
(c) A True but R False
(d) A False but R True
Answer: (c) A True but R False
In simple words: Statement A is true (mitochondria are important cell parts). Statement R is false (they make energy, not food; chloroplasts make food).

🎯 Exam Tip: Avoid confusing the functions of mitochondria (energy production) and chloroplasts (food production via photosynthesis).

III. Match the Following:

 

Question. Match the Following.
Answer:

In simple words: Microscope helps us see things bigger (magnification). Mitochondria are tiny cell parts (micro organelle). Micrometer is a very small unit of measure (small size). Micrographia is a book.

🎯 Exam Tip: Focus on linking each term to its primary definition or associated concept for accurate matching.

IV. Very Short Answer:

 

Question 1. Arrange the following cells in the order of their size: Bacterial cell, Human egg, Frogs egg, Hen's egg.
Answer: When arranged from smallest to largest, the correct order of these cells by size is: Bacterial cell, Human egg, Frogs egg, and then Hen's egg. This sequence clearly shows the range of sizes among different cell types.
In simple words: From smallest to largest, the cells are: Bacterial cell, Human egg, Frogs egg, then Hen's egg.

🎯 Exam Tip: Visualizing the relative sizes of different cells helps in arranging them correctly; bacteria are microscopic, while bird eggs are macroscopic.

 

Question 2. How do you distinguish between living and dead cells?
Answer: Living cells are distinguished from dead cells primarily by the presence of a functional nucleus and metabolic activity. Living cells, like those in onion peel, possess a nucleus and carry out life processes. In contrast, dead cells, such as cork cells, lack a nucleus and active cellular functions.
In simple words: Living cells have a nucleus and are active (like onion peel cells). Dead cells do not have a nucleus and are not active (like cork cells).

🎯 Exam Tip: The presence of a functional nucleus and active metabolism are key indicators for distinguishing living cells from dead ones.

 

Question 3. Name the largest Angiosperm cell
Answer: The largest angiosperm cells are the pulp vesicles found in citrus fruits, such as *Citrus reticulata* (mandarin orange) and *Citrus maxima* (pomelo). These juice sacs are individual cells that are large enough to be easily seen with the naked eye.
In simple words: The biggest angiosperm cells are found in oranges, specifically the juicy parts of fruits like *Citrus reticulata* and *Citrus maxima*.

🎯 Exam Tip: The large size of citrus fruit pulp cells is a surprising and memorable example of a single plant cell.

 

Question 4. Name the organelle without membrane.
Answer: Ribosomes are the cell organelles that do not have a surrounding membrane. They are crucial for protein synthesis in the cell, where genetic information is translated into proteins.
In simple words: Ribosomes are cell parts that do not have a membrane around them.

🎯 Exam Tip: Remembering that ribosomes lack a membrane helps classify them among organelles; they are found in both prokaryotic and eukaryotic cells.

 

Question 5. Identify the following diagram and label A, B, C, D
Answer:The diagram shows the structure of a chloroplast, which is an organelle found in plant cells. A points to the outer membrane, B to the inner membrane. C indicates a Thylakoid, which are sac-like structures, and D refers to the stroma, the fluid-filled space within the chloroplast. These parts are essential for photosynthesis.
In simple words: The picture is of a chloroplast. A is the outer membrane, B is the inner membrane, C is a Thylakoid, and D is the stroma.

🎯 Exam Tip: Be able to identify and label the distinct parts of a chloroplast, as its structure is directly related to its function in photosynthesis.

 

Question 6. Identify the following diagram and label A, B, C
Answer:The diagram shows the structure of a mitochondrion, often called the "powerhouse" of the cell. A points to the outer membrane, which encloses the organelle. B indicates the cristae, which are the inner folds of the inner membrane, increasing its surface area. C refers to the matrix, the fluid-filled space within the inner membrane. These structures are vital for energy production.
In simple words: This picture is of a mitochondrion. A is the outer cover, B is the inner folds called Cristae, and C is the liquid inside called Matrix.

🎯 Exam Tip: Understanding the folded inner membrane (cristae) of mitochondria is important, as it maximizes the surface area for energy-producing reactions.

 

Question 7. Identify the following diagram and label A, B, C, D
Answer:The diagram illustrates the structure of a nucleus, the control center of a eukaryotic cell. A points to the nuclear membrane, which surrounds the nucleus. B indicates a nuclear pore, allowing substances to pass through the membrane. C is the nucleolus, involved in ribosome production. D refers to the chromatin reticulum, which contains the cell's genetic material.
In simple words: This picture shows a nucleus. A is the nuclear membrane, B is a nuclear pore, C is the nucleolus, and D is the chromatin.

🎯 Exam Tip: Remember the nucleus as having a double membrane (nuclear envelope) with pores and containing the nucleolus and chromatin.

 

Question 6. Identify the following diagram and label A, B, C
Answer: The diagram shows a mitochondrion. Label A points to the outer membrane, B points to the cristae (the folds inside), and C points to the matrix, which is the jelly-like substance within. Mitochondria are crucial because they generate most of the energy needed for the cell to function.
In simple words: This picture shows a mitochondrion. A is the outside cover, B is the inner folds, and C is the liquid inside.

🎯 Exam Tip: When identifying cell parts from a diagram, remember the unique features: mitochondria have inner folds called cristae, which is a key identifier.

 

Question 7. Identify the following diagram and label A, В, С
Answer: The diagram illustrates the structure of a cell's nucleus. Label A represents the nuclear membrane, B indicates the nuclear pore, C points to the nucleolus, and D shows the chromatin reticulum. The nucleus is considered the control center of the cell because it stores genetic information and regulates all cell activities.
In simple words: This diagram is of a cell's nucleus. A is its outer skin, B is a small hole in the skin, C is a tiny ball inside, and D is the thread-like material.

🎯 Exam Tip: Clearly label all parts requested, ensuring each label points to the correct structure in the diagram. Double-check if the question asks for A, B, C, D or just A, B, C, and answer accordingly.