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B8 Reproduction

B8 Reproduction. Asexual and sexual reproduction. Asexual reproduction. The process resulting in the production of genetically identical offspring from one parent. Bacteria, fungi and some plants reproduce asexually. Sexual reproduction.

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B8 Reproduction

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  1. B8 Reproduction Asexual and sexual reproduction

  2. Asexual reproduction • The process resulting in the production of genetically identical offspring from one parent. • Bacteria, fungi and some plants reproduce asexually. Sexual reproduction • The process involving the fusion of haploid nuclei to form a diploid zygote and the production of genetically dissimilar offspring

  3. B8 Reproduction Sexual reproduction in Humans

  4. Male reproductive system • Label the male reproductive system with the following organs: • Testes, scrotum, sperm ducts, prostate gland, urethra, penis • State the functions of each of the organs by completing the table provided. Sperm duct Produce the sperm Around the urethra, secrete seminal fluids Penis Passes through the penis to release urine and semen Scrotum

  5. rectum Male reproductive system bladder sperm duct (vas deferens) prostrate gland urethra penis testis scrotum

  6. Female reproductive system • Label the female reproductive system with the following organs: • Ovaries, oviducts, uterus, cervix, vagina • State the functions of each of the organs by completing the table provided. Cervix Where fertilisation occurs; transports ova to uterus Vagina Foetus develops in this muscular organ Ovaries

  7. Female reproductive system oviducts ovaries uterus cervix vagina

  8. Male and female gametes • The human male gamete is called a sperm cell. • The human female gamete is the ovum or egg cell. Sperm Ovum • constantly produced • 1 matures each month Both • 200 – 500 million in one ejaculation • Haploid nucleus -(1 set of single chromosomes) • immotile (moves via cilia) • Contain either X or Y chromosome • Always contain X chromosome • motile • 110μm in diameter • 50μm length

  9. The menstrual cycle • Menstruation is the shedding of the uterine lining (period). • This occurs, on average, every 28 days in women who have gone through puberty. • Females are born with hundreds of immature egg cells in each ovary. • Every month, one follicle (containing an ovum) will mature. This is controlled by hormones from the pituitary gland.

  10. The menstrual cycle – the uterus • Day 1 of the 28 day cycle is the beginning of the period – the endometrium (lining of the uterus) is shed. • After menstruation is complete, the endometrium thickens to prepare for the implantation of the zygote. • If fertilisation occurs, the endometrium will remain thick to nourish the foetus. • If no fertilisation occurs, the endometrium is shed again. • All these changes are controlled by hormones.

  11. The menstrual cycle – the ovaries • During the first half of the 28 day cycle, a follicle in one ovary will mature. • On day 14, the ovum (egg) is released from the ovary and is moved down the oviduct. • The follicle in the ovary continues to make hormones in preparation for implantation. • The ovum will survive for 24h and must be fertilised in this time for pregnancy to occur • If no fertilisation occurs, the ovum is shed in the next period and a new follicle develops. ovulation

  12. Fertilisation • The fusion of a sperm cell and an ovum • Occurs in the oviduct following ovulation • Only one sperm in the millions of sperm ejaculated will fertilise the egg • The nucleus of the sperm joins to the nucleus of the egg, giving the zygote a full set of chromosomes

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