The Fundamental Unit of Life Test - 10

Plant cells have large-sized vacuoles. Swelling of cells happens when the concentration of solutes inside the cell is greater than the concentration of solutes outside the cell. The water enters the cell thorugh Endosmosis (absorption). The shrinkage of cytoplasm occurs due to exo-osmosis in a hypertonic medium.

The energy required for various chemical activities is released by mitochondria. They contain enzymes for cellular respiration. During cellular respiration, energy is released in the form of ATP (Adenosine triphosphate). The body uses energy stored in ATP. Hence, ATP is called the energy currency of the cell. Red Blood Cells in mammals anucleate when mature i.e. they do not contain a nucleus. This is so that the cell has maximum space for haemoglobin. Ribosomes are associated with the synthesis of proteins from amino acids. Proteins are required by a cell for functions such as repair or directing chemical processes.

Eukaryotic cells (Eu means true; karyon means membrane) have a distinct nucleus, nucleolus and a nuclear membrane. Nucleoid is a part of prokaryotic cells.

Plasma membrane, protoplasm and nucleus are living parts of a cell. Cell-wall is made up of cellulose and is a non-living part of a plant cell.

There are two types of Endoplasmic Reticulum (ER). The rough Endoplasmic Reticulum (RER) has ribosomes attached to its surface. Ribosomes are the sites of protein manufacture. The smooth endoplasmic reticulum (SER) helps in the manufacture of fat molecules or lipids. Some of these proteins and lipids help in buliding the cell membrane (known as membrane biogenesis).The Endoplasmic Reticulum also serves other general functions including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus.

Plasma membrane is called semi-permeable because it is selectively permeable and regulates the entry and exit of substances. It allows entry of selective substances into the cell and allows exit of selective substances from the cell.

Chlorophyll is found in chloroplast (green plastids). Chloroplast contains DNA. In plants, DNA or deoxyribonucleic acid is contained within the membrane-bound cell structures of the nucleus, mitochondria and chloroplasts. All plastids are not coloured. Chromoplasts and chloroplasts are coloured plastids whereas leucoplasts are colourless. Nucleus is surrounded by a double membrane - the inner nuclear membrane and the outer nuclear membrane.

B and D are incorrect. According to cell theory, all organisms are made up of cells and cells arise from pre-existing cells.

RBC is called as red blood corpuscles. Red Blood Cells in mammals anucleate when mature i.e. they do not contain a nucleus. This is so that the cell has maximum space for haemoglobin.

Animal cell that do not contain nuclei will also lack in chromosomes. Chromosomes are present inside the nucleus of a cell. Chromosomes contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules.