IGCSE-Biology Exam Revision Questions With Correct Answers

IGCSE-Biology Exam Revision Questions With Correct Answers Define the term transpiration. - Answer-Transpiration is the evaporation of water from the surfaces of the mesophyll cells followed by the loss of water vapor by diffusion from the leaves through the stomata and to the atmosphere. Describe how artificial insemination is carried out. - Answer-collect sperm from male / donor ; inject into uterus ; when egg likely to be in oviduct ; Describe how fertility drugs help women to become pregnant. - Answer-(Fertility drugs may contain) FSH / LH ; taken / injected, during early stage of menstrual cycle ; stimulates ovaries ; (FSH) stimulates follicles to develop ; (LH / FSH) stimulates ovulation ; Describe how meiosis differs from mitosis and explain why meiosis is important for the production of gametes. - Answer-1 two divisions ; 2 four, cells / nuclei / gametes, produced ; 3 halves chromosome number ; 4 (diploid to) haploid ; 5 variation (between cells / nuclei / gametes) ; 6 gametes have different alleles ; 7 gives (more) variation in offspring ; 8 so chromosome number remains the same in next generation ; Describe the advantages of cross-pollination to plants. - Answer-(gives) variation / diversity ; R 'varied species' (plural) ref to, alleles / genes / DNA, from different, plants / idea that increased chance for mutations to be expressed ; allows adaptation to, new conditions / changed environment / AW ; allows evolution to occur ; prevents inbreeding ; ref to disease resistance ; Describe the events that occur in flowering plants after fertilization to form a seed. - Answer-After a zygote forms it divides by mitosis to form an embryo. Each part of the embryo develops into a different structure. Hence the formation of the radicle and plumule. The ovule protecting the embryo develops into a seed. Hence, the formation of the cotyledons and the Testa.