reproduction in humans

Question 1

sexual and asexual reproduction compared

Answer 1

both include mitosis, difference is that asexual does not involve specialised gametes or fertilisation

Question 2

stages of sexual reproduction

Answer 2

gametes produced (through meiosis), male gamete transferred to female gamete, fertilisation, zygote formed (which divides several times by mitosis to form all the new cells of the animal)

Question 3

production of gametes

Answer 3

male and female gametes produced in the sexual organs (testes and ovaries). cells in the organs divide by meiosis to produce the gametes.

Question 4

sperm cells

Answer 4

sac of enzymes to penetrate the membrane of the egg, nucleus, mitochondria to provide energy for movement, flagellum for propulsion

Question 5

mitosis vs meiosis

Answer 5

mitosis produces diploid cells which are genetically identical, meiosis produces haploid cells which are genetically unique

Question 6

main stages of fertilisation

Answer 6

sperm approach the egg, a sperm penetrates the cell membrane and the sperm’s nucleus enters, the fertilisation membrane prevents any more sperm from entering. the sperm and egg nuclei fuse to form a zygote.

Question 7

semen

Answer 7

sperm cells travel along the sperm ducts where they are mixed with a fluid from the seminal vesicles. semen is ejaculated through the urethra into the vagina

Question 8

ovulation

Answer 8

each month an egg is released from the ovaries into the oviduct (fallopian tube)

Question 9

umbilical chord

Answer 9

consists of umbilical artery (carrying deoxygenated blood containing waste products from the fetus to the placenta) and umbilical vein (carrying oxygenated blood containing nutrients from the placenta to the fetus)

Question 10

placenta

Answer 10

allows fetus to obtain oxygen and nutrients from mother’s blood and to get rid of waste products e.g urea and CO2. placenta secretes female hormones, in particular progesterone which maintains the pregnancy and prevents the embryo from aborting.

Question 11

amniotic sac

Answer 11

keeps the amniotic fluid around the developing fetus

Question 12

amniotic fluid

Answer 12

cushions the fetus from mechanical shock and maintains a constant temperature around the fetus

Question 13

pregnancy

Answer 13

membrane called the amniotic sac encloses the developing embryo, secretes a fluid called amniotic fluid. when the fetus becomes recognizably human we call it a fetus. At the end of 9 months of development there is no room for the fetus to grow which sends a hormonal signal to the mother to begin the birth process

Question 14

stages to the birth of a child

Answer 14

1. dilation of the cervix. gets wider to allow the baby to pass through. The muscles of the uterus contract strongly which tears the amniotic sac allowing the amniotic fluid to escape (water breaking)
2. delivery of the baby. strong contractions of the muscles of the uterus push the baby’s head through the cervix and then through the vagina to the outside world.
3. delivery of the afterbirth. after the baby has been born the uterus continues to contract and pushes the placenta out.

Question 15

FSH

Answer 15

follicle stimulating hormone, stimulates the growth of the follicle in the ovaries in girls and stimulates sperm production in boys

Question 16

LH

Answer 16

luteinizing hormone, causes the egg to be released in girls and instructs the testes to secrete testosterone in boys

Question 17

testosterone

Answer 17

controls the development of the male secondary sexual characteristics (see other card for examples)

Question 18

oestrogen

Answer 18

repairs/regrows the lining of the uterus and slows down the production of FSH

produces the female secondary sexual characteristics

Question 19

progesterone

Answer 19

develops and thickens lining of the uterus ready for implantations

Question 20

secondary sexual characteristics in boys

Answer 20

sperm production starts, growth and development of male sexual organs, growth of armpit, pubic hair, chest and facial hair, increase in body mass, growth of muscles, voice breaks, sexual ‘drive’ develops

Question 21

secondary sexual characteristics in girls

Answer 21

menstrual cycle begins, growth and development of female sexual organs, development of ‘rounded’ shape to hips, voice deepens without sudden breaking, breasts develop