Lysosomes are membrane-bound vesicular structures holding a variety of enzymes such as lipases, proteases, and carbohydrases. The purpose of lysosomes is to digest worn out cells. They are involved in the intracellular digestion of foreign food particles and microbes. Sometimes, they also act as suiRead more
Lysosomes are membrane-bound vesicular structures holding a variety of enzymes such as lipases, proteases, and carbohydrases. The purpose of lysosomes is to digest worn out cells. They are involved in the intracellular digestion of foreign food particles and microbes. Sometimes, they also act as suicidal bags. They are involved in the self digestion of cells. They are a kind of waste disposal systems of a cell. On the other hand, vacuoles are storage sacs found in cells. They might store the waste products of cells. In unicellular organisms, the food vacuole contains the consumed food particles. It also plays a role in expelling excess water and some wastes from the cell.
Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes. These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, betweenRead more
Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes.
These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, between the nucleus and the cytoplasm.
Cells are the basic units of life capable of doing all the required biochemical processes that a normal cell has to do in order to live. The basic needs for the survival of all living organisms are the same. All living organisms need to respire, digest food for obtaining energy, and get rid of metabRead more
Cells are the basic units of life capable of doing all the required biochemical processes that a normal cell has to do in order to live. The basic needs for the survival of all living organisms are the same. All living organisms need to respire, digest food for obtaining energy, and get rid of metabolic wastes.
Cells are capable of performing all the metabolic functions of the body. Hence, cells are called the functional units of life.
Multicellular organisms are made up of millions and trillions of cells. All these cells perform specific functions. All the cells specialised for performing similar functions are grouped together as tissues in the body. Hence, a particular function is carried out by a group of cells at a definite plRead more
Multicellular organisms are made up of millions and trillions of cells. All these cells perform specific functions. All the cells specialised for performing similar functions are grouped together as tissues in the body. Hence, a particular function is carried out by a group of cells at a definite place in the body. Similarly, different functions are carried out by different groups of cells in an organism. This is known as division of labour in multicellular organisms.
Prokaryotic cell is a unicellular organism lacking membrane-bound organelles. The characteristics of prokaryotic cells are as follows: 1. Most of them are unicellular. 2. They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 μm. 3. The nuclear region of a prokaryotic cRead more
Prokaryotic cell is a unicellular organism lacking membrane-bound organelles.
The characteristics of prokaryotic cells are as follows:
1. Most of them are unicellular.
2. They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 μm.
3. The nuclear region of a prokaryotic cell is poorly-defined because of the absence of a nuclear membrane. Hence, a prokaryotic cell lacks a true nucleus.
4. The genetic materials of prokaryotic cells are naked. They contain single, circular chromosomes. In addition to the genomic DNA, they have a small, circular plasmid DNA.
5. They have specialised membranous structures called mesosomes. Mesosomes are formed by the invagination of the cell membrane. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells.
6. Membrane-bound cell organelles such as mitochondria, plastids, and endoplasmic reticulum are absent from a prokaryotic cell.
7. Most prokaryotic cells contain a three-layered structure – outermost glycocalyx, middle cell wall, and the innermost plasma membrane. This structure acts as a protective unit.
Examples of prokaryotic cells include blue green algae, bacteria, etc.
Plasma membrane is the outermost covering of the cell that separates it from the environment. It regulates the movement of substances into the cell and out from it. It allows the entry of only some substances and prevents the movement of other materials. Hence, the membrane is selectively-permeable.Read more
Plasma membrane is the outermost covering of the cell that separates it from the environment. It regulates the movement of substances into the cell and out from it. It allows the entry of only some substances and prevents the movement of other materials. Hence, the membrane is selectively-permeable.
Movement of neutral solutes across the cell membrane – Neutral molecules move across the plasma membrane by simple passive diffusion. Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration.
Movement of polar molecules across the cell membrane – The cell membrane is made up of a phospholipid bilayer and proteins. The movement of polar molecules across the non-polar lipid bilayer requires carrier-proteins. Carrier-proteins are integral protein particles having certain affinity for specific solutes. As a result, they facilitate the transport of molecules across the membrane.
Mesosome is a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane. Its functions are as follows: 1. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughtRead more
Mesosome is a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane. Its functions are as follows:
1. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells.
2. It also increases the surface area of the plasma membrane to carry out various enzymatic activities.
3. It helps in secretion processes as well as in bacterial respiration.
(c) Membrane-bound organelles are organelles surrounded by a double membrane. Nucleus, mitochondria, chloroplasts, etc., are examples of such organelles. These cell organelles are absent from prokaryotes. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/bioloRead more
(c) Membrane-bound organelles are organelles surrounded by a double membrane. Nucleus, mitochondria, chloroplasts, etc., are examples of such organelles. These cell organelles are absent from prokaryotes.
(c) According to the biogenic theory, new cells can only arise from pre-existing cells. Only complete cells, in favourable conditions, can give rise to new cells. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
(c) According to the biogenic theory, new cells can only arise from pre-existing cells. Only complete cells, in favourable conditions, can give rise to new cells.
(a) Robert Brown did not discover the cell. The cell was discovered by Robert Hook. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
(a) Robert Brown did not discover the cell. The cell was discovered by Robert Hook.
Both lysosomes and vacuoles are endomembrane structures, yet they differ in terms of their functions. Comment.
Lysosomes are membrane-bound vesicular structures holding a variety of enzymes such as lipases, proteases, and carbohydrases. The purpose of lysosomes is to digest worn out cells. They are involved in the intracellular digestion of foreign food particles and microbes. Sometimes, they also act as suiRead more
Lysosomes are membrane-bound vesicular structures holding a variety of enzymes such as lipases, proteases, and carbohydrases. The purpose of lysosomes is to digest worn out cells. They are involved in the intracellular digestion of foreign food particles and microbes. Sometimes, they also act as suicidal bags. They are involved in the self digestion of cells. They are a kind of waste disposal systems of a cell. On the other hand, vacuoles are storage sacs found in cells. They might store the waste products of cells. In unicellular organisms, the food vacuole contains the consumed food particles. It also plays a role in expelling excess water and some wastes from the cell.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
What are nuclear pores? State their function.
Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes. These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, betweenRead more
Nuclear pores are tiny holes present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes.
These holes allow specific substances to be transferred into a cell and out from it. They allow molecules such as RNA and proteins to move in both directions, between the nucleus and the cytoplasm.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
Cell is the basic unit of life. Discuss in brief.
Cells are the basic units of life capable of doing all the required biochemical processes that a normal cell has to do in order to live. The basic needs for the survival of all living organisms are the same. All living organisms need to respire, digest food for obtaining energy, and get rid of metabRead more
Cells are the basic units of life capable of doing all the required biochemical processes that a normal cell has to do in order to live. The basic needs for the survival of all living organisms are the same. All living organisms need to respire, digest food for obtaining energy, and get rid of metabolic wastes.
Cells are capable of performing all the metabolic functions of the body. Hence, cells are called the functional units of life.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
Multicellular organisms have division of labour. Explain.
Multicellular organisms are made up of millions and trillions of cells. All these cells perform specific functions. All the cells specialised for performing similar functions are grouped together as tissues in the body. Hence, a particular function is carried out by a group of cells at a definite plRead more
Multicellular organisms are made up of millions and trillions of cells. All these cells perform specific functions. All the cells specialised for performing similar functions are grouped together as tissues in the body. Hence, a particular function is carried out by a group of cells at a definite place in the body. Similarly, different functions are carried out by different groups of cells in an organism. This is known as division of labour in multicellular organisms.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
What are the characteristics of prokaryotic cells?
Prokaryotic cell is a unicellular organism lacking membrane-bound organelles. The characteristics of prokaryotic cells are as follows: 1. Most of them are unicellular. 2. They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 μm. 3. The nuclear region of a prokaryotic cRead more
Prokaryotic cell is a unicellular organism lacking membrane-bound organelles.
The characteristics of prokaryotic cells are as follows:
1. Most of them are unicellular.
2. They are generally small in size. The size of a prokaryotic cell varies from 0.5 – 5 μm.
3. The nuclear region of a prokaryotic cell is poorly-defined because of the absence of a nuclear membrane. Hence, a prokaryotic cell lacks a true nucleus.
4. The genetic materials of prokaryotic cells are naked. They contain single, circular chromosomes. In addition to the genomic DNA, they have a small, circular plasmid DNA.
5. They have specialised membranous structures called mesosomes. Mesosomes are formed by the invagination of the cell membrane. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells.
6. Membrane-bound cell organelles such as mitochondria, plastids, and endoplasmic reticulum are absent from a prokaryotic cell.
7. Most prokaryotic cells contain a three-layered structure – outermost glycocalyx, middle cell wall, and the innermost plasma membrane. This structure acts as a protective unit.
Examples of prokaryotic cells include blue green algae, bacteria, etc.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
How do neutral solutes move across the plasma membrane? Can the polar molecules also move across it in the same way? If not, then how are these transported across the membrane?
Plasma membrane is the outermost covering of the cell that separates it from the environment. It regulates the movement of substances into the cell and out from it. It allows the entry of only some substances and prevents the movement of other materials. Hence, the membrane is selectively-permeable.Read more
Plasma membrane is the outermost covering of the cell that separates it from the environment. It regulates the movement of substances into the cell and out from it. It allows the entry of only some substances and prevents the movement of other materials. Hence, the membrane is selectively-permeable.
Movement of neutral solutes across the cell membrane – Neutral molecules move across the plasma membrane by simple passive diffusion. Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration.
Movement of polar molecules across the cell membrane – The cell membrane is made up of a phospholipid bilayer and proteins. The movement of polar molecules across the non-polar lipid bilayer requires carrier-proteins. Carrier-proteins are integral protein particles having certain affinity for specific solutes. As a result, they facilitate the transport of molecules across the membrane.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
What is a mesosome in a prokaryotic cell? Mention the functions that it performs.
Mesosome is a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane. Its functions are as follows: 1. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughtRead more
Mesosome is a convoluted membranous structure formed in a prokaryotic cell by the invagination of the plasma membrane. Its functions are as follows:
1. These extensions help in the synthesis of the cell wall, replication of DNA. They also help in the equal distribution of chromosomes into the daughter cells.
2. It also increases the surface area of the plasma membrane to carry out various enzymatic activities.
3. It helps in secretion processes as well as in bacterial respiration.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
Which of the following is correct:
(c) Membrane-bound organelles are organelles surrounded by a double membrane. Nucleus, mitochondria, chloroplasts, etc., are examples of such organelles. These cell organelles are absent from prokaryotes. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/bioloRead more
(c) Membrane-bound organelles are organelles surrounded by a double membrane. Nucleus, mitochondria, chloroplasts, etc., are examples of such organelles. These cell organelles are absent from prokaryotes.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
New cells generate from
(c) According to the biogenic theory, new cells can only arise from pre-existing cells. Only complete cells, in favourable conditions, can give rise to new cells. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
(c) According to the biogenic theory, new cells can only arise from pre-existing cells. Only complete cells, in favourable conditions, can give rise to new cells.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
Which of the following is not correct?
(a) Robert Brown did not discover the cell. The cell was discovered by Robert Hook. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/
(a) Robert Brown did not discover the cell. The cell was discovered by Robert Hook.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-8/