REPRODUCTION OF LIVING THINGS Flashcards
What is meant by sex? (2)
The sex of an organism has a genetic basis. In mammals, it depends on the absence or presence of an activated gene, SRY, located on the Y chromosome.
What is a zygote? (1)
Cell that is produced from 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 two haploid nuclei to form the nucleus of a zygote and contains the chromosomes from both gametes.
What is the karyotype of a female? (1)
XX
How oogenesis and spermatogenesis is different, in terms of timing? (3)
Oogenesis- from puberty till menopause a few primary oocytes undergo meiosis 1 to become secondary oocytes only one of these forms a Graafian follicle, the others degenerate.
Spermatogenesis- millions of sperm are formed daily.
How are spermatogenesis and oogenesis different, in terms of the process by meiosis? (2)
Oogenesis- meiosis 2 stops at prophase until fertilisation occurs with the haploid nucleus of the sperm cell, then it undergoes the rest of meiosis 2.
Spermatogenesis- sperm cells undergo both meiosis 1 and meiosis 2 in sperm production.
How are oogenesis and spermatogenesis different, in terms of the number of gametes? (1)
Oogenesis- one ovum is produced from each oogonium.
Spermatogenesis- 4 spermatozoa are produced from each spermatogonium.
What is a gamete? (1)
Cells containing half the number of chromosomes.
How are oogenesis and spermatogenesis different, in terms of release? (2)
Oogenesis-the Graafian follicle releases a secondary oocytes into the oviduct at ovulation.
Spermatogenesis- sperm are released from the body by ejaculation.
How are oogenesis and spermatogenesis different, in terms of development? (3)
Oogenesis- oogonia become surrounded by follicle cells forming tiny primary follicles that remain dormant in the oviduct. Most fail to develop further, they degenerate.
Spermatogenesis- all spermatozoa become sperm cells they are nurtured by the somatic cell and the fibrous tubules of the testes.
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 form from the time of puberty throughout adult life.
What occurs during the first round of meiosis in spermatogenesis? (1)
The primary spermatocytes develop into secondary spermatocytes. They are the same size.
What occurs during the second round of meiosis in spermatogenesis? (1)
Secondary spermatocytes undergo meiosis 2 and develop into 4 haploid spermatids.
What occurs during the first round of meiosis in oogenesis? (1)
Primary oocytes develops into a secondary oocytes and the first polar body that degenerates
What is meant by maturation in terms of the process of gametogenesis? (1)
Involves meiosis and the production of haploid gametes
What is meant by proliferation, in terms of the process of gametogenesis? (2)
In which cells present in a layer called the germinal epithelium divide by mitotic cell division. This division is repeated to reproduce cells capable of becoming gametes.
What happens in the growth stage, in terms of spermatogenesis? (1)
The spermatogonia develop into primary spermatocytes.
What occurs in the second round of meiosis in oogenesis? (1)
Second oocytes develop into develop into a large ovum and a secondary polar body which is lost.
What happens in the growth stage of oogenesis? (1)
Oogonium develop into primary oocytes.
What is the germinal epithelium? (1)
A layer of cells that undergoes continues cell division.
What are the sequences of both the male and female processes of gametogenesis? (3)
-maturation (proliferation)
-growth
-multiplication
What is a gonad? (1)
A reproductive organ that produces gametes.
What are the female gonads? (2)
The ovaries that produce ova.
What are the male gonads? (1)
The testes that produce spermatids.
What process are sperm cells produced by? (1)
Spermatogenesis.
