(a) What is a cell?
(b) Describe briefly the structure of DNA.
(c) Describe the process of mitosis
(d) What is the importance of mitosis to living organisms?
Explanation
(a) A Cell can be defined as the basic structural and eg. Cool, Wood functional unit of a living organism. Or it could be Volcanoes referred to as the smallest unit of living organism or Diffusion basic unit of life
(b) Structure of DNA: DNA consist Carbon dioxide In of two chains of nucleotides, twisted into each other the atmosphere p n to form a double helix. Each nucleotide is made up Putrefaction of a phosphate group alternating with sugar molecule or deoxyribose, a nitrogenous base or (cytosine, Dead /4 Respiration and deca adenine, guanine, thymine) or purines and y/ Photosynthesis Green manure and plant residue pyrimidines. The nitrogenous base from one chain link up with a compatible base of the opposite chain Dead and or adenine with thymine, guanine with cytosine. The DNA is like a rung of a ladder through a hydrogen teal decay of plants Plants bond. Absorption through roots
(c) Description of the process of mitosis: Mitosis occurs. in somatic cells or body cells or meristematic cells. Inorganic salts of carbonates In soil At the beginning of mitosis or prophase nuclear membrane and nucleolus disappear. Chromosomes Losses in form of carbonates become more visible, the chromosomes replicate. of metals like calcium and potassium They are normally made up of two strands or chomatids, spindles are formed. Chromosomes are then arranged at the equator or middle of the cell or ) metaphase. The chromosomes attach themselves at the centromere to the spindle and chromatids separate at the centromere. Each member of the pair move to the opposite pole of the cell or anaphase. The two sets of chromatid grouped together at the opposite pole and become less visible or Telophase . The nuclear membrane reappears including the nucleolus. The cytoplasm constrict in animals cells to form daughter cells. In plant cells, wall is formed between two sets of chromatids. Then two daughter cells are formed.
(d) Importance of mitosis to living organisms:
(1) Mitosis helps in the growth or development.
(2) It assist in Repair of cells
(3) It also ensures exact copy of DNA or sum total of inherited factors or transmission of genes to the daughter cells or ensures consistency of DNA. )