Chapter 43

sexual reproduction examples

- a sperm cells from a male rabbit fertilizes the egg of a female rabbit - fertilization occurs when two fish release their gametes into the water - two earthworms exchange sperm resulting in both earthworms' eggs being fertilized

asexual reproduction examples

- a sponge grows mitotically produced buds that grown into new sponges - an amoeba produces two identical daughter cells via mitosis - a whip tail lizard's offspring develops from an unfertilized egg

budding

- formation of offspring from outgrowths that break free or remain attached to form a colony - used by hydras

parthenogenesis

- growing and developing of embryo from unfertilized egg - seen in some fish

gamete

- haploid - sperm cell

luteinizing hormone in women

- induces ovulation - stimulates formation of the corpus luteum

Testosterone functions

- inhibition of GnRH secretion - growth of pubic hair - fat distribution

endoderm

- inner layer of the embryo - lines the respiratory tract - forms the lungs

progesterone

- maintains uterine lining for pregnancy - stops ovarian cycle when pregnant

Both spermatogenesis and oogenesis

- meiosis is involved - haploid daughter cells are produced

mesoderm

- middle layer of the embryo - forms the muscles, bones, and cartilage - forms the kidneys and gonads

oogenesis

- one daughter cell becomes a gamete and the others become polar bodies - process begins before birth

ectoderm

- outer layer of the embryo - forms the CNS - forms the epidermis, nails, and hair

spermatogenesis

- process ends at death - millions of daughter cells are produced daily

fission

- replacement of parent by two equal offspring - used by prokaryotic microorganisms

fragmentation

- splitting of an organism into body parts that each grown the rest of the missing body parts - observed in sponges

luteinizing hormone (LH) function in males

- stimulation of Leydig cells - production of testosterone

follicle-stimulating hormone function in males

- stimulation of sertoli cells - sperm production

Zygote

- the fertilized egg - diploid cell resulting from fertilization

estrogen

- triggers secondary sex characteristics - decline in production induces menopause - high levels increase LH secretion during follicular phase

Place the steps of fertilization in the order that they occur.

1. a mature oocyte is ovulated and moves down the fallopian tube 2. a sperm cell passes through the follicle cells surrounding the oocyte 3. a portion of the zona pellucia is digested by enzymes found within the acrosome, located on the tip of the sperm cell 4. a sperm cell binds to and fuses with the plasma membrane of the egg 5. the haploid nucleus of the sperm enters the cytoplasm of the egg 6. the sperm and the egg nuclei fuse to form a zygote 7. the developing embryo is implanted on the inner lining of the uterus

What is the difference between asexual reproduction and sexual reproduction?

Asexual reproduction produces genetically identical offspring, whereas sexual reproduction produces offspring that are genetically different from each other and from their parents.

What part of the menstrual cycle? In response to rising estrogen levels, luteinizing hormone promotes the release of the oocyte from the follicles in the ovary.

day 14

What part of the menstrual cycle? The shedding of the inner lining of the uterus that would have supported implantation and early embryo growth had fertilization occurred.

days 1-5

What part of the menstrual cycle? The inner lining of the uterus is prepared for implantation in response to increased levels of progesterone.

days 15-28

What part of the menstrual cycle? The inner lining of the uterus grows in response to increased levels of estrogen produced by the maturing follicles.

days 6-13

What gland is responsible for producing both follicle-stimulating hormone (FSH) and luteinizing hormone (LH)?

pituitary gland

Which statement best describes ovulation?

release of a secondary oocyte from a mature follicle

In which type of environment is external fertilization most likely to occur?

river (water)

What is the function of Sertoli cells found within the seminiferous tubules located within the testes?

support, nourish, and regulate the production of sperm

Follicle-stimulating hormone (FSH) in women

triggers initial follicle growth

Identify the scenario that best describes parthenogenesis.

Male bees develop from unfertilized eggs.

fertilization

a process fusing the two nuclei of two gametes