SEXUAL REPRODUCTION IN ANIMALS Flashcards
What is a zygote? (1)
the cell formed by the fusion of two gametes.
what are the differences between oogenesis and spermatogenesis? (7)
-time of arrival
-development
-timing
-number of gametes
-release
-process of meiosis
-structure
what is fertilisation? (1)
the fusion of the nuclei of two gametes to form the nucleus of a zygote, contains the chromosomes from both gametes.
what is the karyotype of a female? (1)
XX
What is meant by the sex? (2)
the sex of an organism has a genetic basis in mammals, it depends on the absence or presence of a activated gene, SRY, located on the Y chromosome.
what happens in the growth stage in terms of oogenesis? (1)
cells develop from oogonia to primary oocytes.
what process are sperm cells produced by? (1)
spermatogenesis
what are the female gonads? (2)
gonads; ovaries
and produce gametes called ova (singular ovum)
what are the male gonads? (2)
gonads; testes
produce gametes called spermatoza (singular spermatozoon)
what is a gonad? (1)
an animal organ that produces gametes.
what are the sequences of both the male and female processes of gametogenesis? (3)
-multiplication (proliferation)
-growth
-maturation
what is the germinal epithelium? (1)
a single layer of cells (epithelium) that undergoes regular mitosis, producing other cells.
what occurs during the second round of meiosis in oogenesis? (1)
meiosis 2 of the secondary oocyte produces a large ovum and a smaller polar body which is lost.
what happens in the growth stage, in terms of spermatogenesis? (1)
cells develop from the spermatogonia to primary spermatocytes.
what occurs during the first round of meiosis in oogenesis? (1)
the primary oocyte produces one haploid secondary oocyte and a smaller, haploid polar body which is lost.
what occurs during the second round of meiosis in spermatogenesis? (1)
both secondary spermatocytes undergo meiosis 2 to produce 4 gametes.
what occurs during the first round of meiosis in spermatogenesis? (1)
the primary spermatocyte produces haploid secondary spermatocytes that are the same size.
how are oogenesis and spermatogenesis different, in terms of time of arrival? (2)
oogenesis - oogonia formed in the embryonic ovaries long before birth.
spermatogenesis - spermatogonia formed from the time of puberty throughout adult life.
how are oogenesis and spermatogenesis is different, in terms of development? (3)
oogenesis - oogenesis becomes surrounded by follicle cells forming tiny primary follicles and remain dormant within the ovary cortex. most fail to develop further, they degenerate.
spermatogenesis - all spermatogonia develop into sperm, nurtured by the Sertoli cells in the seminiferous tubules of the testes.
how are oogenesis and spermatogenesis different, in terms of release? (2)
oogenesis - the graafian follicle releases a secondary oocyte into the oviduct at ovulation.
spermatogenesis - sperm are released from the body by ejaculation.
what is meant by maturation in terms of the process by gametogenesis? (1)
which involves meiosis and results in formation of haploid gametes.
what is a gamete? (1)
cells carrying half the number of chromosomes.