3.1.1 Genes, Deoxyribonucleic Acids (DNA) and Chromosomes

3.1 Cell Division 3.1.1 Genes, Deoxyribonucleic Acids (DNA) and Chromosomes 1. The nucleus of a cell contains many small thread-like structures called chromosomes.   2. Chromosomes always exist in pairs (except in gametes).   3. Each chromosome contains a molecule of a deoxyribonucleic acid (DNA).   4. On each chromosome, there are genes which are the basic hereditary units. … Read more

Form 4 Science Chapter 5 – Sex Determination and the Occurrence of Twins (Structured Questions 2)

Question 1:Diagram 1 shows the schematic diagram of sex determination in human being.(a) In Diagram 1, complete the sex chromosomes in gametes K and L. [2 marks](b) What is gamete L? [1 mark](c) State process B. [1 mark](d) State the sex of offspring M. [1 mark](e) Based on Diagram 1, state the percentage to get … Read more

Formative Practice 5.3 – Form 4 Science (KSSM) Chapter 5

Question 1:What is mutation? Answer:Mutation is a change that occurs spontaneously and randomly on the genes or chromosomes, which can cause a characteristic change in the child inheriting the modified genetic materials. Question 2:List three factors that cause mutation. Answer:Radioactive radiation, X-ray and toxic chemical substances. Question 3:List the advantages and disadvantages of genetic research. … Read more