D3.1 - human reproduction (5g)

Question 1

what is the role of meiosis in the sexual life cycle?

Answer 1

meiosis breaks up the parental combination of alleles
- produces haploid gamete cells in a reduction division, meaning only half the genes from a parent can be passed onto the offspring

Question 2

what is the role of fertilisation in the sexual life cycle?

Answer 2

fertilisation produces new combinations of alleles
- fusion of the haploid gametes nuclei restores the diploid number of chromosomes, as homologous pairs with one coming from the male parent and the other from the female parent

Question 3

what are the characteristics of sexual reproduction?

Answer 3

• involves 2 parents
• fusion of male and female gametes
• new allele combination which leads to genetic variation in the offspring, unique to both parents
• cell division involves meiosis
• chromosome numbers are halved during gamete formation and re-established during fertilisation
• usually slower and requires more energy
• new allele combination provides variation needed for adaption to the changed environment

Question 4

what are the characteristics of asexual reproduction?

Answer 4

• involves 1 parent
• no fusion of gametes
• no new allele combinations , so offspring are genetically identical to the parent
• cell division involves mitosis or binary fission
• chromosome numbers are maintained throughout
• usually faster and requires less energy
• production of genetically identical offspring allows colonization by individuals that are already adapted to the existing environment

Question 5

what are the characteristics of males in sexual reproduction?

Answer 5

• gamete is small and motile to efficiently move to the female gamete
• gamete has less food reserves
• releases millions of gametes
• males typically mate with females as they aren’t involved in parental care and breeding success is often based on having large numbers of offspring

Question 6

what are the characteristics of females in sexual reproduction?

Answer 6

• gamete is large and immotile
• gametes contain enough nutrients to support early development of the embryo
• females tend to choose mates with particular traits that indicate health and ability to provide support and breeding success is based on the quality of parental care

Question 7

what are the components of the female reproductive system?

Answer 7

ovary
oviduct
uterus
endometrium
cervix
vagina

Question 8

what are the components of the male reproductive system?

Answer 8

vas deferens
seminal vesicle
prostate gland
epididymis
urethra
testis

Question 9

what is the function of the ovary?

Answer 9

where oocytes mature prior to ovulation and from where oestradiol and progesterone are secreted into the bloodstream

Question 10

what is the function of the oviduct?

Answer 10

transports the oocyte/early embryo from the ovary to the uterus

Question 11

what is the function of the uterus?

Answer 11

the muscular organ where the early embryo implants and develops

Question 12

what is the function of the endometrium?

Answer 12

vascular inner lining of the uterus wall

Question 13

what is the function of the cervix?

Answer 13

muscular opening, allowing the sperm to enter and a route for childbirth

Question 14

what is the function of the vagina?

Answer 14

muscular passage leading from the external genitalia to the uterus, where semen is released during sexual intercourse

Question 15

what is the function of the vas deferens?

Answer 15

muscular duct which transports the sperm from epididymis to the urethre during ejaculation

Question 16

what is the function of the seminal vesicle?

Answer 16

gland that contributes to the formation of semen, providing fluid for the sperm

Question 17

what is the function of the prostate gland?

Answer 17

secretes an alkaline fluid to neutralise vaginal acids and maintain sperm viability

Question 18

what is the function of the epididymis?

Answer 18

where sperm matures and becomes motile and is stored until ejaculation

Question 19

what is the function of the urethra?

Answer 19

conducts sperm and semen outside the body through the penis during ejaculation

Question 20

what is the function of the testis?

Answer 20

produces sperm, within the seminiferous tubules, and secretes testosterone into the bloodstream

Question 21

where does fertilisation occur?

Answer 21

fertilisation occurs in the oviduct or the fallopian tube

Question 22

what is the process of fertilisation?

Answer 22

1. sperm enter the oviduct and move towards the egg due to chemotaxis
2. acrosome reaction allows sperm to penetrate the zona pellucida
3. one sperm’s plasma membrane fusses with the egg’s plasma membrane
4. sperm’s nucleus enters the egg, while vesicles released from the egg destroy the sperm tail and mitochondria
5. the egg nucleus completes meiosis II
6. dissolution of the nuclear membrane of the sperm and egg nuclei
7. all the condensed chromosomes from the egg and sperm undergo a joint mitosis to produce 2 diploid nuclei