Cell - The Unit of Life Test 13

Structure of centrosome

Centrosome is a small naked organelle found in the cytoplasm of animal cell near the outer surface of the nucleus. It consists of two bundles of microtubules called centrioles that lie at right-angles to each other. Centrioles are short cylinders and possess a whorl of 9 peripheral fibrils. The fibrils are absent in the centre. Each fibrils are made of 3 sub-fibres. There is a proteinaceous hub in the central part of a centriole.

Q. How many membranes surround a centriole structure?

Structure of centrosome

Centrosome is a small naked organelle found in the cytoplasm of animal cell near the outer surface of the nucleus. It consists of two bundles of microtubules called centrioles that lie at right-angles to each other. Centrioles are short cylinders and possess a whorl of 9 peripheral fibrils. The fibrils are absent in the centre. Each fibrils are made of 3 sub-fibres. There is a proteinaceous hub in the central part of a centriole.

Q. Out of the two centrioles in the sperm, the distal centriole forms:

Structure of centrosome

Centrosome is a small naked organelle found in the cytoplasm of animal cell near the outer surface of the nucleus. It consists of two bundles of microtubules called centrioles that lie at right-angles to each other. Centrioles are short cylinders and possess a whorl of 9 peripheral fibrils. The fibrils are absent in the centre. Each fibrils are made of 3 sub-fibres. There is a proteinaceous hub in the central part of a centriole.

Q. The main structure of centriole is:

Structure of centrosome

Centrosome is a small naked organelle found in the cytoplasm of animal cell near the outer surface of the nucleus. It consists of two bundles of microtubules called centrioles that lie at right-angles to each other. Centrioles are short cylinders and possess a whorl of 9 peripheral fibrils. The fibrils are absent in the centre. Each fibrils are made of 3 sub-fibres. There is a proteinaceous hub in the central part of a centriole.

Q. The central hub is connected to the triplets through:

Structure of centrosome

Centrosome is a small naked organelle found in the cytoplasm of animal cell near the outer surface of the nucleus. It consists of two bundles of microtubules called centrioles that lie at right-angles to each other. Centrioles are short cylinders and possess a whorl of 9 peripheral fibrils. The fibrils are absent in the centre. Each fibrils are made of 3 sub-fibres. There is a proteinaceous hub in the central part of a centriole.

Direction : In the following questions the Assertions (A) and Reasons (R) have been put forward. Read both the statements and choose the correct option from the following:

Assertion : Centrioles are the self-duplicating bodies. They contain DNA and RNA.

Reason : The centrioles are converted into basal bodies which give rise to cilia and flagella.

Fluid mosaic model was proposed by Singer and Nicolson. According to this model, there is a central lipid bilayer of phospholipids with their polar head group towards the outside and the non-polar tails pointing inwards. Some proteins are embedded in the lipid layer are called integral or intrinsic proteins and they cannot be separated from the membrane. There are large globular integral proteins which project beyond the lipid layer on both the sides. Superficially attached proteins are called extrinsic or peripheral proteins and can be easily removed. Some membrane lipids and integral proteins remains bound to oligosaccharides which project into the extracellular fluid.

Q. The passage of substances across the cell membrane occurs by:

Fluid mosaic model was proposed by Singer and Nicolson. According to this model, there is a central lipid bilayer of phospholipids with their polar head group towards the outside and the non-polar tails pointing inwards. Some proteins are embedded in the lipid layer are called integral or intrinsic proteins and they cannot be separated from the membrane. There are large globular integral proteins which project beyond the lipid layer on both the sides. Superficially attached proteins are called extrinsic or peripheral proteins and can be easily removed. Some membrane lipids and integral proteins remains bound to oligosaccharides which project into the extracellular fluid.

Q. The interaction responsible for stabilizing plasma membrane is majorly:

Fluid mosaic model was proposed by Singer and Nicolson. According to this model, there is a central lipid bilayer of phospholipids with their polar head group towards the outside and the non-polar tails pointing inwards. Some proteins are embedded in the lipid layer are called integral or intrinsic proteins and they cannot be separated from the membrane. There are large globular integral proteins which project beyond the lipid layer on both the sides. Superficially attached proteins are called extrinsic or peripheral proteins and can be easily removed. Some membrane lipids and integral proteins remains bound to oligosaccharides which project into the extracellular fluid.

Q. The structure of membranes is:

Fluid mosaic model was proposed by Singer and Nicolson. According to this model, there is a central lipid bilayer of phospholipids with their polar head group towards the outside and the non-polar tails pointing inwards. Some proteins are embedded in the lipid layer are called integral or intrinsic proteins and they cannot be separated from the membrane. There are large globular integral proteins which project beyond the lipid layer on both the sides. Superficially attached proteins are called extrinsic or peripheral proteins and can be easily removed. Some membrane lipids and integral proteins remains bound to oligosaccharides which project into the extracellular fluid.

Q. Who proposed the fluid mosaic model of plasma membrane?

Fluid mosaic model was proposed by Singer and Nicolson. According to this model, there is a central lipid bilayer of phospholipids with their polar head group towards the outside and the non-polar tails pointing inwards. Some proteins are embedded in the lipid layer are called integral or intrinsic proteins and they cannot be separated from the membrane. There are large globular integral proteins which project beyond the lipid layer on both the sides. Superficially attached proteins are called extrinsic or peripheral proteins and can be easily removed. Some membrane lipids and integral proteins remains bound to oligosaccharides which project into the extracellular fluid.

Direction : In the following questions the Assertions (A) and Reasons (R) have been put forward. Read both the statements and choose the correct option from the following:

Assertion : The plasma membrane is selectively permeable.

Reason : It allows solvents and solutes to pass through it.

German botanist, Matthias Jacob Schleiden in 1838, observed different parts of the plants under the microscope and found that all of them are made up of cells. German zoologist, Theodor Schwann in 1839, observed parts of the animal body and noticed that cells had an outer layer which is also called as plasma membrane. Schleiden and Schwann together gave cell theory. This theory slates that bodies of all living organisms are made up of cells and their products. Rudolf Virchow studied that all cells arise from the pre-existing cells. In other words, the existing cells divide to form new cells. He stated this in Latin as “omnis cellula-e-cellula” and on this basis proposed the modern cell theory.

Q. Schleiden and Schwann were respectively

German botanist, Matthias Jacob Schleiden in 1838, observed different parts of the plants under the microscope and found that all of them are made up of cells. German zoologist, Theodor Schwann in 1839, observed parts of the animal body and noticed that cells had an outer layer which is also called as plasma membrane. Schleiden and Schwann together gave cell theory. This theory slates that bodies of all living organisms are made up of cells and their products. Rudolf Virchow studied that all cells arise from the pre-existing cells. In other words, the existing cells divide to form new cells. He stated this in Latin as “omnis cellula-e-cellula” and on this basis proposed the modern cell theory.

Q. Idea of individuality of cell as well as the concept of the cell was

German botanist, Matthias Jacob Schleiden in 1838, observed different parts of the plants under the microscope and found that all of them are made up of cells. German zoologist, Theodor Schwann in 1839, observed parts of the animal body and noticed that cells had an outer layer which is also called as plasma membrane. Schleiden and Schwann together gave cell theory. This theory slates that bodies of all living organisms are made up of cells and their products. Rudolf Virchow studied that all cells arise from the pre-existing cells. In other words, the existing cells divide to form new cells. He stated this in Latin as “omnis cellula-e-cellula” and on this basis proposed the modern cell theory.

Q. One of the following contributed cell lineage to cell doctrine

German botanist, Matthias Jacob Schleiden in 1838, observed different parts of the plants under the microscope and found that all of them are made up of cells. German zoologist, Theodor Schwann in 1839, observed parts of the animal body and noticed that cells had an outer layer which is also called as plasma membrane. Schleiden and Schwann together gave cell theory. This theory slates that bodies of all living organisms are made up of cells and their products. Rudolf Virchow studied that all cells arise from the pre-existing cells. In other words, the existing cells divide to form new cells. He stated this in Latin as “omnis cellula-e-cellula” and on this basis proposed the modern cell theory.

Q. One of the following is exception to cell theory

German botanist, Matthias Jacob Schleiden in 1838, observed different parts of the plants under the microscope and found that all of them are made up of cells. German zoologist, Theodor Schwann in 1839, observed parts of the animal body and noticed that cells had an outer layer which is also called as plasma membrane. Schleiden and Schwann together gave cell theory. This theory slates that bodies of all living organisms are made up of cells and their products. Rudolf Virchow studied that all cells arise from the pre-existing cells. In other words, the existing cells divide to form new cells. He stated this in Latin as “omnis cellula-e-cellula” and on this basis proposed the modern cell theory.

Direction : In the following questions the Assertions (A) and Reasons (R) have been put forward. Read both the statements and choose the correct option from the following:

Assertion : Cell theory states that unit of life is cell.

Reason : Robert Hooke was the first to coin the term cell.