The Fundamental Unit of Life

Both the statements are correct about cell wall. Cell wall is made of a complex carbohydrate called cellulose. It is hard and rigid.

This is correct. Cell membrane or plasma membrane allows only selected materials to move in and out of the cell.

This is the correct matching. Cells were first discovered by Robert Hooke in 1665. Leeuwenhoek observed free cells like bacteria for the first time. Robert Brown discovered the nucleus in the cell. J.E. Purkinje coined the term ‘protoplasm’ for the fluid substance of the cell. M. Schleiden and T. Schwann proposed the cell theory that all plants and animals are composed of cells and that cell is the basic unit of life.

This statement is incorrect about nucleus. Nucleolus is formed of RNA, which is required for protein synthesis in the cytoplasm. Chromatin forms the chromosomes during cell division. Chromatin material is mainly formed of DNA. Genes are segments of DNA.

No, this is incorrect. A gene is a functional unit of DNA/chromosome which controls one or many functions of an organism. Sometimes a set of many genes may control a single function.

A cell gains water from outside in a hypertonic solution. A cell loses water by osmosis in a hypotonic solution. Both these statements are incorrect. This is the correct answer choice.

SER or smooth endoplasmic reticulum helps in the manufacture of fat molecules or lipids. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis.

This is the correct answer. The Golgi apparatus, or Golgi complex, functions as a factory in which proteins received from the ER are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion. In addition, as noted earlier, glycolipids and sphingomyelin are synthesised within the Golgi. In plant cells, the Golgi apparatus further serves as the site at which the complex polysaccharides of the cell wall are synthesised. Thus, all these are the functions of Golgi apparatus.

No, this is incorrect. Lysososmes  are involved in the digestion of materials from within the cell. Mitochondria are the power house of the cell. They are not involved in digestion.

Lysosomes are not present in all plant cells. They are absent in yeast, fungi and green algae. They are also absent in RBCs. Thus, this statement is incorrect.

Vacuoles are storage sacs for solid or liquid contents. This is the only correct statement.

Both these statements are incorrect. Plastids are double membrane bounded. They do not have a cristae. The internal organisation of the plastids consists of numerous membrane layers embedded in a material called the stroma.

This is the correct answer. The main function of mitochondria in aerobic cells is the production of energy by synthesis of ATP. Mitochondria have their own genetic material and the facility to produce their own ribonucleic acids (RNAs) and proteins. Mitochondrial DNA carries genes necessary for the synthesis of many, but not all, mitochondrial proteins.

The internal organisation of the plastids consists of numerous membrane layers embedded in a material called the stroma. Leucoplasts are primarily organelles in which materials such as starch, oils and protein granules are stored. Thus, this is the correct answer.

This is the correct answer as all the statements given above are correct. Chromoplasts are coloured plastids. Leucoplasts are colourless plastids. Leucoplasts are involved in the formation and storage of starch and oil drops.

This is the correct answer. The largest cell in the human body is the nerve cell.

This is incorrect. Mitochondria - powerhouse of the cell. Endoplsmic reticulum - internal transport system of the cell

Endocytosis is an energy-using process by which cells absorb molecules (such as proteins) by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane. Ameoba obtains its food through endocytosis.

The cytoplasm is the fluid content inside the plasma membrane. It also contains many specialised cell organelles. Each of these organelles performs a specific function for the cell.

This is the correct answer. Golgi apparatus is involved in the formation of lysosmes.

This is the correct answer as both these statements are correct. Chromosomes are composed of DNA and protein. Chromosomes contain information for inheritance of features from parents to next generation in the form of DNA (deoxyribo nucleic acid) molecules.

CO₂ is the cellular waste that needs to be excreted out by the cell. It accumulates in high concentrations inside the cell. In the cell’s external environment, the concentration of CO₂ is low as compared to that inside the cell. As soon as there is a difference of concentration of CO₂ inside and outside a cell, CO₂ moves out of the cell, from a region of high concentration to a region of low concentration outside the cell by the process of diffusion.
Thus, this is the correct answer.
 

This is the correct answer. The flexibility of the cell membrane  enables the cell to engulf in food and other materials from its external environment. Such a process is known as endocytosis. Amoeba acquires its food through this process.

Rough endoplasmic reticulum has ribosomes on its surface for synthesising proteins. Ribosomes make the endoplasmic reticulum rough.

This is the correct matching. Eukaryotic cell contains nucleolus. Prokaryotic cell contains nucleoid. RNA is required for protein synthesis in the cytoplasm.