Chapter 15: Sexual Reproduction,Development and Growth

Question 1

scientific name of sperm duct

Answer 1

vas deferens

Question 2

structure of testes

Answer 2

• each seminiferous consist of primordial germ cells
• primordial germ cells undergo cell division to produce sperm
• Sertoli cells within the wall of seminiferous tubule provide nutrients
• sperm is transported to epididymis
• flows out through sperm duct (vas deferens)

Question 3

spermatogenesis scheme

Answer 3

1. primordial germ cell divide mitotically into diploid spermatogonium
2. spermatogonium develop and expend into diploid primary spermatocyte
3. primary spermatocyte undergo meiosis 1 to form two haploid secondary spermatocyte
4. secondary spermatocyte undergo meiosis 2 to form two haploid spermatids
5. spermatid undergo differentiation to form sperm

Question 4

oogenesis

Answer 4

• primordial germ cell divide mitotically to form diploid oogonium
• oogonium develop into primary oocyte with primary follicle
• during fetal development, primary oocyte undergo meiosis 1 but stop at prophase 1
• upon reaching puberty, primary oocyte continues meiosis 1 to form secondary oocyte with secondary follicle and a first polar body
• secondary oocyte undergo meiosis 2 and stop at metaphase 2
• the first polar body complete meiosis 2 to form two second polar bodies
• the secondary follicle will develop into Graafian follicle
• (ovulation) matured Graafian follicle approach to surface of ovary and release the secondary oocyte to the fallopian tube
• after ovulation, the remaining follicle form corpus lutem
• once the sperm penetrate it, the secondary oocyte will complete meiosis 2 to form ovum and first polar body
• fertilisation occur when nucleus of sperm fuses with nucleus of ovum to produce diploid zygote
• the rest of the polar bodies die and will be disintegrated by the ovary
• with fertilisation, corpus luteum continue to grow and secrete oestrogen and progesterone
• without fertilisation, corpus luteum and secondary oocyte degenerate and die, removed during menstruation

Question 5

early development of embryo

Answer 5

zygote undergo multiples division through mitosis

• the first cell divide mitotically into two-cell embryo
• the following cell division produce morula
• morula transform into blastocyst
• implant in the endometrium wall (implantation)
• continue to grow into embryo

Question 6

Human Chorionic Ganodotropin (HCG) Hormone

Answer 6

• doubled every 2-3 days for first 4 weeks of pregnancy
• to ensure the secretion of progesterone and oestrogen
• can be detected in urine

Question 7

2 importance of placenta

Answer 7

• exchange site of substance between foetus and mother

- replace corpus luteum to secrete oestrogen and progesterone to maintain thickness of endometrium wall

Question 8

3 types of twins

Answer 8

• identical
• fraternal
• conjoined

Question 9

treatment for blocked fallopian tube

Answer 9

• through surgery

- In Vitro fertilisation (IVT)

Question 10

4 stages in complete metamorphosis

Answer 10

1. egg
2. larvae
3. pupa
4. adult

Question 11

growth of butterfly`

Answer 11

1. adult butterfly produce eggs
2. caterpillar (larvae) hatched from the eggs
3. eat leaves to grow into pupa
4. rapid development in pupa stage
5. butterfly emerges from pupa with soft and folded wings
6. mature into adult butterfly

Question 12

6 phrases in sigmoid curve

Answer 12

1. lag - adjustment to new sources in the surrounding
2. exponential - high growth rate and rapid cell division
3. stationary - reach maximum size and undergo differentiation
4. maturity - zero growth rate, cell division for repair cell
5. senescence - negative growth rate due to aging
6. death - aging, illness, lack of nutrients

Question 13

how does ecdysis occur

Answer 13

• new exoskeletal form underneath the old ones
• insect sucks in air to expand its body
• break the old exoskeletal and new one will emerge
• expand its body one more time by sucking in air before the new exoskeletal harden