Distinguish between mutations, mutants, and mutagens.  (3mks)

Mutations are sudden, spontaneous, and permanent changes in an individual’s genetic material; 

Mutants are individuals who develop and exhibit unusual characteristics that were not previously present in the population due to mutations; mutagens are factors in the environment that cause the mutations to occur;

Give two causes of mutations (2mks)

• radiation such as gamma rays and ultraviolet rays;
• chemical substances such as mustard gas and other heavy metals (mercury, lead, asbestos);
• sudden extreme high or low temperatures;
• 
  

Describe the causes and effects of chromosomal mutations (15mks)

Deletion; refers to the absence of a portion of a chromosome; it results from breakage and falling off of a portion of a chromosome; leading to the loss of a group of genes that may have a disastrous effect on the development of an organism;

Inversion; refers to the reversal of the normal sequence of genes in a portion of a chromosome; occurs when a middle portion of a chromosome breaks, turns,the  or rotates (inverts) through 180o and joins up again; this does not change the genetic constitution of the organism; but may bring into proximity genes whose combined effects to an organism produce a beneficial effect to an organism, or cause disadvantages to the organism;

Translocation; attachment of a portion of a chromosome to a non-homologous chromosome; occurs when a chromosome breaks and the portion joins another non- homologous chromosome; this may lead to serious consequences, even death depending on what genes are missing;

Duplication; situation where a set of genes is represented twice in a chromosome; a part of a chromatid formed during cell division may replicate further to form an extra piece; which may attach onto the same or another chromatid; resulting to traits controlled by some genes being excessively expressed;

Non-disjunction; this is the failure of a pair of homologous chromosomes to separate during the first stage of meiosis; resulting in one of the daughter cells formed after the division of the cell having two of one kind of chromosome; while the other cell has less or none; diseases or disorders known as syndromes are known to result from this aberration e.g. Down’s Syndrome (Mongolism), Turner’s Syndrome, Klinefelter’s Syndrome; Polyploidy; this is the presence of more than two sets of chromosomes in a cell; occurs due to a failure of a cell to divide after the first stage of meiosis or after the chromosomes have replicated in mitosis; common in plants than animals; in plants, it causes some improvements such as resistance to drought, certain diseases and pests, improved yields and early maturity; 

Discuss the various ways in which anaerobic respiration is utilized in industries and homes.(20mks)

Bread making; yeast is used to ferment sugar in wheat flour into carbon (IV) oxide and energy; the carbon (IV) oxide is produced in form of bubbles that causes the dough to rise and become porous; 

Beer making; yeast is used to ferment sugars in malt/grapes/fruits; to form beer, wines and spirits; 

Sewage treatment; anaerobes break down raw sewage and harmful industrial effluents; to harmless products of water, energy/heat and carbon (IV) oxide; 

Silage formation; vegetation is fermented by bacteria to produce nutritious and good-scented/flavoured animal feed that increases production/yields;

Production of acids and strong liquors; special bacteria and fungi ferment food products; to produce acids such as citric acid, oxalic acid and vinegar; the products are used as food preservatives and flavouring agents; 

Manufacture of dairy products; under controlled environments; anaerobes help in fermentation hence manufacture of milk products such as butter, cheese, ghee and yoghurt; 

Production of fuels such as biogas; and gasohol; cane sugar is fermented by yeast; to produce gasohol for running engines or operating machinery; animal wastes such as guano and cow dung; can be used to produce a mixture of methane and carbon (IV) oxide gas; by exposing it to fermentation agents; methane is used to run simple machines such as water pumps and for cooking;

Production of fermented porridge and milk; maize or wheat flour and milk is exposed to microbes in the air, which ferment it; to produce sour and sweet tasting porridge or milk; 

Production of compost manure in agriculture, microorganisms breakdown organic matter to release nutrients for crops; 

Pharmaceutical industry; utilizes anaerobic respiration to produce drugs such as penicillin