Olympiad Test: Cell Structure And Functions - UPSC MCQ

Mitochondria is known as powerhouse of the cell because it is responsible for the extracting energy from food through cellular respiration.The energy is released in the form of adenosine triphosphate (ATP).

D is the correct option.Plastids are considered the kitchen of the cell. Some plastids, known as chloroplasts, are found in plants.

The functional unit of life is called a Cell.
Explanation:
- Cells are the basic structural and functional units of all living organisms.
- They are the building blocks of life and are responsible for carrying out all the essential functions necessary for an organism's survival.
- Cells are capable of performing various functions such as metabolism, growth, reproduction, and response to stimuli.
- Each cell contains a nucleus, which houses the genetic material (DNA) that carries the instructions for the cell's activities.
- Cells can be classified into two main types: prokaryotic cells (lack a nucleus) and eukaryotic cells (have a nucleus).
- Prokaryotic cells are found in bacteria and archaea, while eukaryotic cells are found in plants, animals, fungi, and protists.
- Cells work together to form tissues, organs, and organ systems, allowing for the complex organization and functioning of multicellular organisms.
- The study of cells is known as cell biology or cytology.
- Understanding the structure and function of cells is crucial for understanding the processes of life and for advancements in fields such as medicine and biotechnology.

Chloroplast is found in the:


There are four options given and we need to determine which one is correct.
A: Plant cell only
- Chloroplasts are specialized organelles found in plant cells.
- They are responsible for photosynthesis, the process by which plants convert sunlight into energy.
B: Animal cell only
- Animal cells do not contain chloroplasts.
- They obtain energy through other means such as cellular respiration.
C: Both of these
- This option is not correct because chloroplasts are only found in plant cells, not animal cells.
D: None of these.
- This option is also not correct because chloroplasts are indeed found in plant cells.
Conclusion:
- The correct answer is A: Plant cell only.
- Chloroplasts are unique to plant cells and play a crucial role in the process of photosynthesis.

The control unit of a cell is the nucleus.
The nucleus is often referred to as the control center of the cell because it contains the cell's genetic material, DNA, which carries the instructions for the cell's activities. Here is a detailed explanation of why the nucleus is the control unit of a cell:
1. Contains genetic material (DNA): The nucleus houses the cell's DNA, which contains the instructions for making proteins and carrying out cellular functions. DNA is organized into structures called chromosomes, and each chromosome contains many genes.
2. Directs cellular activities: The DNA in the nucleus serves as a blueprint for the cell's activities. It directs the synthesis of proteins through a process called gene expression. Proteins are essential for carrying out various cellular functions, such as enzyme activity, cell signaling, and structural support.
3. Regulates gene expression: The nucleus controls which genes are expressed (activated) and which are not. This regulation is crucial for the proper functioning of cells and ensures that only the necessary proteins are produced at the right time and in the right amounts.
4. Replication and transmission of genetic material: The nucleus is responsible for the replication and transmission of genetic material during cell division. Before a cell divides, its DNA is replicated in the nucleus, and each newly formed cell receives a copy of the genetic material.
5. Protection of DNA: The nucleus is surrounded by a double membrane called the nuclear envelope, which acts as a protective barrier for the DNA. This membrane contains pores that allow the movement of molecules in and out of the nucleus, facilitating communication and transport between the nucleus and other cellular compartments.
In conclusion, the nucleus is the control unit of a cell because it contains the genetic material and regulates the cell's activities through gene expression. It plays a vital role in directing cellular functions and ensures the proper functioning and survival of the cell.

Single-celled organisms are called Unicellular.

Explanation:
To provide a detailed solution, let's break down the question and answer choices:
1. Question:
- The question states that single-celled organisms are being referred to.
2. Answer Choices:
- The answer choices are as follows:
- A: Unicellular
- B: Multicellular
- C: Both of these
- D: None of these
3. Explanation:
- Single-celled organisms consist of only one cell, which means they are composed of a single unit of life.
- The term "Unicellular" accurately describes these organisms, as it literally means "consisting of a single cell."
- Multicellular organisms, on the other hand, are composed of multiple cells, meaning they are made up of more than one unit of life.
- The answer choice B, "Multicellular," is incorrect because it refers to organisms that have multiple cells, which contradicts the question's focus on single-celled organisms.
- The answer choices C and D are also incorrect because they do not accurately describe single-celled organisms.
Therefore, the correct answer is A: Unicellular, as it accurately describes single-celled organisms.

Answer:

Tissue is a group of cells.

Explanation:
The correct answer to the question is option B: Group of cells. Here's a detailed explanation of why tissue is a group of cells:
1. Tissue definition: Tissue refers to a group or collection of similar cells that work together to perform a specific function in the body.
2. Cell definition: A cell is the basic structural and functional unit of all living organisms. It is the smallest unit of life and can carry out various functions necessary for the survival and functioning of an organism.
3. Tissue composition: Tissues are composed of a group of cells that are similar in structure and function. These cells are organized and work together to perform a specific task or function in the body.
4. Types of tissues: There are four main types of tissues in the human body: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Each type of tissue is composed of specific cells that have specialized functions.
5. Functions of tissues: Tissues play a vital role in maintaining the structure and function of organs and systems in the body. They provide support, protection, and coordination of various activities.
In conclusion, tissue is a group of cells that work together to perform a specific function in the body. It is an essential component of the human body and is responsible for the proper functioning of organs and systems.

Discovery of the Cell

• Robert Hooke: The correct answer is B. Robert Hooke.


• Robert Hooke was an English scientist who made significant contributions to the field of biology.


• In 1665, Hooke published his book called "Micrographia" in which he described his observations using a compound microscope.


• He coined the term "cell" to describe the small, box-like structures he observed in a thin slice of cork under the microscope.


• Hooke's discovery of cells marked a significant milestone in the development of cell theory, which states that all living organisms are composed of cells.

Therefore, it was Robert Hooke who discovered the cell.

Option C, because both of them have irregular shape, hence can change their shape.

The correct answer is D: Cell.
Explanation:
A hen's egg is a single cell surrounded by a protective shell. Let's explore this in more detail:
1. Structure of a Hen's Egg:
- Shell: The outermost layer of the egg is the hard shell, which provides protection.
- Egg White (Albumen): The egg white surrounds the yolk and acts as a cushioning and protein-rich environment.
- Yolk: The yolk is the nutrient-rich part of the egg, providing essential nutrients for the developing embryo.
- Chalaza: The chalaza is a pair of spiral bands that anchor the yolk in the center of the egg.
2. Cell Composition:
- The egg is a single cell, known as the ovum or oocyte, which is produced by the hen's reproductive system.
- It is a specialized cell containing all the necessary components for development, including genetic material (DNA) and organelles.
- The ovum is fertilized by sperm from a rooster to initiate the development of an embryo.
3. Development:
- When a hen's egg is fertilized, the single cell starts dividing and multiplying, forming a complex organism.
- The fertilized egg undergoes a series of cell divisions, differentiation, and growth, eventually forming various tissues, organs, and organ systems.
In summary, a hen's egg is initially a single cell (ovum) that has the potential to develop into a complex organism. Therefore, the correct answer is D: Cell.

Cell as the Structural Unit of Living Beings

In order to determine if the statement "Cell is the structural unit of living beings" is true or false, we need to understand the concept of a cell and its role in living organisms.

1. Definition of a Cell

• A cell is the basic building block of all living organisms.


• It is the smallest structural and functional unit of life.


• Cells can be microscopic or visible to the naked eye.

2. Function of Cells

• Cells carry out essential functions necessary for the survival of living organisms.


• They perform various biochemical reactions, produce energy, and maintain homeostasis.


• Cells are responsible for growth, development, and reproduction.

3. Cell Types

• There are two main types of cells: prokaryotic and eukaryotic cells.


• Prokaryotic cells are simpler and lack a nucleus, while eukaryotic cells have a nucleus and are more complex.

4. Cellular Organization

• Cells are organized in a hierarchical manner to form tissues, organs, and organ systems within an organism.


• The organization of cells allows for specialized functions and efficient coordination.

5. Evidence Supporting Cell as the Structural Unit

• Microscopic examination of various organisms reveals the presence of cells as the fundamental structural unit.


• Cell theory, proposed by Schleiden and Schwann in the 19th century, states that all living organisms are composed of cells.


• Advancements in scientific techniques, such as microscopy and molecular biology, continue to provide evidence supporting the cell as the structural unit of living beings.

Conclusion

Based on the definition of a cell, its functions, the presence of cells in all living organisms, and the evidence provided by scientific research, we can conclude that the statement "Cell is the structural unit of living beings" is true.

Explanation:
The given statement is false. Animal cells do not have a rigid cell wall like plant cells. Instead, animal cells are surrounded by a flexible cell membrane that provides shape and protection to the cell. Here is a detailed explanation:
Differences between plant and animal cells:
1. Cell wall:
- Plant cells have a rigid cell wall composed of cellulose, which provides structural support to the plant.
- Animal cells do not have a cell wall; instead, they have a flexible cell membrane made up of lipids and proteins.
2. Shape:
- Plant cells have a fixed shape due to the rigid cell wall, which maintains the structural integrity of the cell.
- Animal cells have a variable shape and can change their shape as needed. The absence of a cell wall allows them to be more flexible.
3. Function:
- The cell wall in plant cells provides mechanical support, protection, and helps to maintain turgor pressure.
- The cell membrane in animal cells regulates the movement of substances in and out of the cell, and also plays a role in cell signaling and recognition.
4. Permeability:
- The cell wall in plant cells is porous and allows the passage of water, ions, and other molecules.
- The cell membrane in animal cells is selectively permeable, controlling the movement of substances and maintaining the internal environment of the cell.
In conclusion, animal cells do not have a rigid cell wall like plant cells. They are surrounded by a flexible cell membrane that provides shape and protection to the cell.

The instrument used to see the tiny objects is called a microscope.
Explanation:
- The statement is True.
- A microscope is an instrument used to magnify and observe tiny objects that are not visible to the naked eye.
- It consists of a combination of lenses and light sources that allow the user to view objects at a high magnification.
- Microscopes are commonly used in scientific research, medical laboratories, and educational settings to study cells, microorganisms, and other small structures.
- There are different types of microscopes, such as compound microscopes, electron microscopes, and stereo microscopes, each with its own specific uses and capabilities.
- The invention of the microscope revolutionized the field of biology and has greatly contributed to our understanding of the microscopic world.
- In conclusion, a microscope is the instrument of choice when it comes to observing tiny objects.

Plants cells have bigger Vacuoles because they need more water, organic and inorganic substances in each cell to function proper as they do not have much variety of cells as we do.
Therefore, the given statement  is false.

ostrich egg cells are the largest isolated single cell. It can be seen by naked eyes because its size ranges from 130mm-170mm

The cell was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to cellula or small rooms which monks inhabited, thus deriving the name. However what Hooke actually saw was the dead cell walls of plant cells (cork) as it appeared under the microscope.

Amoeba is an example of a multicellular organism.
Explanation:
- Amoeba is a type of single-celled organism known as a protist.
- It belongs to the group of organisms called unicellular organisms, which means they are composed of a single cell.
- Multicellular organisms, on the other hand, are composed of multiple cells that work together to form tissues, organs, and organ systems.
- Examples of multicellular organisms include animals, plants, and fungi.
- Amoeba, being a single-celled organism, does not fit into the category of multicellular organisms.
- It lives as a single cell and carries out all its necessary functions within that single cell.
- Amoeba reproduces asexually by a process called binary fission, where one cell divides into two identical daughter cells.
- It does not have specialized cells or tissues like multicellular organisms do.
- Therefore, the statement that Amoeba is an example of a multicellular organism is false.

Protoplasma is called as the living substance of the cell because  cell comprises of nucleus, cytoplasm, cell membrane and cell wall. Nucleus, cytoplasm, cell membrane are living part, and they are together called Protoplasm.
So, the given statement is false

Tissue that connects, supports, binds, or separates other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibres, and including cartilaginous, fatty, and elastic tissues.

The nucleus is often referred to as the control center, or brain, of the cell and contains the DNA, or genetic material. Cells that contain these features (ie, cytoskeleton, organelles surrounded by cytoplasm and nucleus surrounded by nuclear envelope) are called eukaryotic cells. Human cells are eukaryotic cells.