16. Reproduction
A section of Biology, 0610
Listing 10 of 757 questions
During puberty, the hormones oestrogen and testosterone are involved in the development of the secondary sexual characteristics. State the name of the gland that produces each hormone. oestrogen testosterone Complete Table 3.1 by placing ticks (✓) in the boxes to show which hormones are involved in the development of each secondary sexual characteristic. Table 3.1 secondary sexual characteristic testosterone oestrogen body shape changes breast development facial hair voice deepening is a diagram of the uterus during pregnancy. A B C D State the letter on that identifies the structure which performs each of these functions. • exchange of substances between the fetus and the mother • protects the fetus from mechanical shock • transfers blood between the fetus and the placenta Outline the processes involved in labour and birth. The birthweights of 75 rats were measured and recorded within different birthweight ranges. The number of rats in each birthweight range is recorded in Table 3.2. Table 3.2 birthweight / g number of rats 5.5 – 5.9 6.0 – 6.4 6.5 – 6.9 7.0 – 7.4 7.5 – 7.9 8.0 – 8.4 8.5 – 8.9 State the most common birthweight range in Table 3.2. State the number of rats that are heavier than 6.9 g at birth in Table 3.2. State the type of variation shown by the data in Table 3.2.
0610_s22_qp_33
THEORY
2022
Paper 3, Variant 3
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Describe the role of progesterone in pregnancy. shows a drawing of a section of a human placenta. The arrows show the direction of blood flow. from mother maternal artery space filled with maternal blood maternal vein fetal capillary not to scale to mother umbilical arteries umbilical vein from fetus from fetus to fetus Substances move across the placenta by diffusion. State the names of two useful substances that move from the blood of the mother to the blood of the fetus. Using the information in , suggest how the placenta is adapted for efficient diffusion. The Rhesus (Rh) factor is a protein that is found on the surface of red blood cells in some people. If the protein is present then the individual is Rh positive. The allele for the presence of the Rh factor is dominant and is represented by the letter D. The recessive allele is represented by the letter d. If a mother is Rh negative and the fetus is Rh positive there can be problems during pregnancy. A Rh negative mother and a heterozygous Rh positive father have a child. Complete the Punnett square and determine the probability of the child being Rh positive. father’s gametes mother’s gametes probability
0610_s23_qp_43
THEORY
2023
Paper 4, Variant 3
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For Examiner's Use The production of human gametes involves the type of nuclear division known as meiosis. State two reasons why meiosis is suitable for gamete production. The sex of a human fetus is determined by the sex chromosomes, X and Y. shows the determination of sex in four different examples. Examples 3 and 4 show sex determination in twins. example gametes zygote X X XX cell from a fetus XX + X Y XY XY + X X XX XX + X X XX XX + X X XX XX XX + For Examiner's Use Use 5.1 to explain how the sex of a fetus is determined. Examples 3 and 4 show two ways in which twins are formed. The twins in example 3 are identical. Use to explain why. During the development of a fetus, different genes are expressed at different times. Explain what is meant by the term development. For Examiner's Use One of the genes that controls the ability of blood to clot is found only on the X chromosome. XH represents an X chromosome with the dominant allele for normal blood clotting. Xh represents an X chromosome with the recessive allele which causes the blood to clot slowly. The Y chromosome is small and does not have the gene for blood clotting. Here is a list of four genotypes. XHXH, XHXh, XHY, XhY Choose the genotype from the list that matches each of the following: ● gives a phenotype of long clotting time; ● is heterozygous; ● is homozygous. Haemophilia is a rare genetic condition in which the blood clots very slowly. In the USA, haemophilia affects 1 in 5000 male births each year. In some cases these births occur in families where the condition has not occurred before. Explain how boys can have haemophilia when the condition has not previously existed in their family.
0610_w13_qp_32
THEORY
2013
Paper 3, Variant 2
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Questions Discovered
757