YR 10 GENETICS REVISION: Answer sheet 2012 1. State four examples of inherited traits in humans. EG: hair colour, eye colour, height, shape of the nose. Infinite answers are possible. 2. Copy the table and match the following terms with their definitions: Gene, traits, chromosome, DNA, Genetics, Asexual reproduction, Meiosis, homozygous, heterozygous, allele, phenotype, genotype Term Definition traits Characteristics passed from parents to offspring chromosomes Thread like structures in the nucleus which carry the genes. allele Alternative forms of a gene Gene A part of a chromosome that carries an instruction homozygous Pure breeding for a characteristic eg: TT for tall DNA Deoxyribonucleic acid Genetics Study of Heredity Phenotype The appearance of an individual Geneotype The alleles an individual has for a particular gene. meiosis Two cell divisions resulting in sex cells that contain half the normal number of chromosomes Asexual Formation of new individuals without the production of reproduction sex cells heterozygoys Hybrid (containing two different alleles) eg: Tt (tall) 3. Answer True or False a) A chromosome is found in the nucleus of a cell. (True) b) In ordinary cell division (Mitosis), each cell formed has the same number of chromosomes as the parent cell. (True) c) A gamete is a sex cell. (true) d) A sex cell has the same number of chromosomes as the parent cell. (false) e) Meiosis produces sex cells in humans, animals and plants. (true) f) Many genes are carried on a chromosome. (true) g) If a mosquito has 6 chromosomes in their body cells they will have 12 chromosomes in their sex cells. (false)
4. Compare Mitosis and Meiosis. Mitosis No. of divisions 1 No. chromosomes in daughter cells. No. of daughter cells Where it occurs Some as original 2 Somatic cells
Meiosis 2 Half original 4 gametes
5. a) b) c) 6. a) b) c) d)
How many chromosomes are in the following:a normal body cell (46) a body cell of a person with Down’s Syndrome (47) a sex...