2021 Exam

Question 1

explain the role of the nucleus in protein synthesis

Answer 1

• nucleus controls all cellular activities
• DNA makes up chromosomes
• Information in a gene is transcribed into mRNA
• Nucleus transmits mRNA to the cytoplasm
• Ribosomes, used for synthesis are produced in the nucleus.

Question 2

what are the roles of accessory glands in the male reproductive system

Answer 2

• Aid in the transport of sperm
• Secrete a milky alkaline fluid
• increase pH of vagina
• Protect sperm from acidity of the vagina

Question 3

Describe the role of the acrosome during the first stage of fertilisation

Answer 3

• Acrosome comes into contact with the oocyte
• Acrosome releases enzymes
• Enzymes breakdown zona pellucida
• Sperm nucleus enters oocyte

Question 4

what is the role of the corpus museum in the ovarian and menstrual cycles

Answer 4

• Secretes oestrgogen
• Progesterone thickens the endometrium
• Inhibits the release of FSH

Question 5

Using an example, explain how negative feedback controls the level of hormones in the blood.

Answer 5

• Negative feedback occurs when the release of one substance decreases the release of another substance.
• An increase in oestrogen feedback to the pituitary gland to decrease the secretion of FSH

Question 6

why would it be surprising that a female gets a sex-linked recessive disorder rather than a male

Answer 6

• More common for males to have sex-linked disorders than females

Question 7

Why is it advantageous to have blood in a cavity rather than a blood vessel;

Answer 7

• chorionic villi will be surrounded by mother blood
• Increase SA:VOL ratio for chorionic villi to access blood
• This enhances diffusion

Question 8

why would women experiencing a low-lying placenta often deliver her baby via a caesarean

Answer 8

• The placenta is blocking the exit of the baby
• Placenta may rupture
• Mother may suffer blood loss and the baby may suffer oxygen depreviation

Question 9

PFO is given to incomplete closure of the foramen ovale. Discuss importance of the foramen ovale and the possible implications of PFO.

Answer 9

• Foramen ovale allows blood to bypass the lungs
• As the lungs are not functioning, the heart will receive oxygen from the mother
• implications can include shortness of breath and fatigue.

Question 10

how is oxygen transferred from the blood into the cells

Answer 10

• tissue fluid has a low concentration of oxygen compared to blood
• Oxygen will disassociate from oxyhaemoglobin to form haemoglobin and oxygen
• oxygen moves by diffusion into tissue fluid
• from tissue fluid will diffuse into cells

Question 11

how is glucose transferred from the blood into the cells

Answer 11

• active transport
• energy required
• glucose will attach to the binding site of a carrier protein.
• The carrier protein will change shape and release glucose on the other side of the membrane

Question 12

what role does the environment play in epigenetics

Answer 12

• environmental stimuli can change the epigenome
• an agent such as stress

Question 13

what is a random assortment

Answer 13

• Pairs of chromosomes are random
• The way one pair of chromosomes split, doesn’t affect the others

Question 14

five similarities between mitosis and meiosis

Answer 14

• both are types of cell division
• both start with a diploid cell
• both have similar substages
• DNA replication occurs before mitosis/meiosis during interphase
• sister chromatids separate in mitosis and meiosis II

Question 15

five differences between mitosis and meiosis - must be linked

Answer 15

mitosis -
- daughter cells identical
- one division
- results in two daughter cells
- homologous chromosomes do not pair
- no crossing over

meiosis -
- daughter cells not identical
- two division
- results in four daughter cells
- homologous chromosomes pair
- crossing over