Level: JHS, Basic 9 | Subject: Integrated Science | Strand: Diversity of Matter | Topic: Genetics and Heredity (Living Cells)
Read the summary notes first: Basic 9 Integrated Science Summary Notes: Genetics and Heredity
Test Yourself: 20 Objective Questions
Tick one answer for each question, then press Review answer. If your answer is wrong, it will be marked first, then the correct answer will show in green.
Essay Questions
- Explain the meaning of each of these terms: heredity, nucleus, chromosome, gene and DNA. (5 marks)
- Explain how the sex of a baby is determined. (5 marks)
- Distinguish between inherited and acquired characteristics. Give two examples of each in humans. (6 marks)
- In pea plants, tall (T) is dominant over short (t). Show the offspring of a cross between two plants with genotype Tt, and state the ratio of tall to short plants. (6 marks)
- Give two ways a farmer can use the knowledge of heredity to improve crops or animals. (4 marks)
Essay Questions: Marking Guide for Teachers and Parents
- (5 marks, 1 each) Heredity is the passing of characteristics from parents to offspring. The nucleus is the control centre of the cell that holds the chromosomes. A chromosome is a thread-like structure made of DNA and protein. A gene is a section of DNA that carries the instruction for one characteristic. DNA is the chemical that carries genetic information, shaped like a twisted ladder.
- (5 marks) Females have XX and males have XY (1). Every egg from the mother carries an X (1). A sperm from the father carries either X or Y (1). If an X sperm fertilises the egg, the baby is a girl, XX (1). If a Y sperm fertilises the egg, the baby is a boy, XY (1).
- (6 marks) Inherited characteristics are passed from parents through genes (1). Examples: eye colour, blood group, skin colour (1 mark for two). Acquired characteristics are gained during life from the environment and are not passed on through genes (2 marks for a correct definition, 1 for a partly correct one). Examples: a scar, ability to swim, knowing a language (1 mark for two). The inherited definition is also worth 2 marks, so the total is 2 + 1 + 2 + 1 = 6.
- (6 marks) Gametes from each parent: T and t (1). Offspring genotypes: TT, Tt, Tt, tt (2). Phenotypes: three tall plants and one short plant (2). Ratio 3 tall to 1 short, or 3:1 (1).
- (4 marks) Any two ways, 2 marks each (the way and a short explanation). Examples: selecting seeds from the best plants so good traits pass on; cross-breeding to combine good traits such as disease resistance and high yield; breeding fast-growing cattle or high-laying hens.
Education Always (education.inspiringalways.com). Original practice questions, not official WAEC or BECE questions.