Sexual Reproduction

Two types:

• sexual
• asexual

Asexual §

• Types:

  • Binary fission
  • fragmentation
  • spore formation
  • vegetative propagation
  • cloning
  • parthenogenesis

• Process resulting in the production of genetically identical offspring from one parent without fusion of gametes

• Offspring are called clones

Sexual Reproduction §

• Fertilisation

  • Fusion of the gamete

• Gametes -> have half of the chromosomes

• Requires fertilisation

  • Fusion of the nuclei of an ovum and a sperm to form a zygote

• Produces genetically dissimilar offspring

Sexual Characteristics §

• traits which distinguish between the sexes
• organs of the reproductive organs you are born with
• Sex Organs:
  • Testes -> Male
  • Ovaries -> Female

Secondary Sexual Characteristics §

• Secondary sexual characteristics appear during puberty
• Sex hormones are produced by the sex organs or gonads
• Gonads produces sex cells or gametes

Terms	Males	Females
Sex organs/Gonads	Testes	Ovaries
Sex cells/Gametes	Sperm	Ova
Sex Hormones	Testosterone	Oestrogen

• Puberty:
  • period of rapid growth and development
  • prepare the body for sexual reproduction
  • Sex hormones produced in both sexes, throughout lifetime
  • Production of the respective sex hormones increase during puberty

Males	Females
Testes and penis increase in size	Uterus and vagina enlarge
Production of sperm begins	Menstrual cycle, including ovulation, begins
Larynx enlarges, voice deepens	Breasts enlarge
Facial, body, armpit and public hair appear	Armpit and pubic hair appear
Shoulders and chest broaden	Hips widen
Muscle mass increases	Fat deposits in buttocks, thighs and hips increases
Growth spurt	Growth spurt
Oil and sweat glands increases secretion, causes acne and body odour	Oil and sweat glands increases secretion, causes acne and body odour

Male Reproductive System §

• Seminal vesicle
• Prostrate gland
• Cowper’s gland
  • Produce nutrient rich slightly alkaline seminal fluid
  • Seminal fluid
    • Mixes with sperm to form semen at the urethra
    • Promotes the survival of sperm
    • Provides a medium for sperm to swim in
    • Rich in fructose and zinc
    • Mucus lubricates vagina
    • Proteins for antimicrobial functions
• Scrotum
  • hold testes outside the body
  • Maintain lower temperature for optimum sperm development
• Epididymis
  • Stores inactive sperm
• Ureter
• Urinary bladder
• Sperm duct
  • Deliver sperm
• Urethra
• Penis
  • Erectile organ that fills with blood during arousal
  • Enters vagina when erect to deposit semen
• Testis
  • Produce sperm and testosterone

Female Reproductive System §

• Ureter
• Urinary bladder
• Urethra
• Oviduct/Fallopian tube
  • Oviducts transport immotile ovum down by:
    • Peristalsis of the oviduct muscles
    • Sweeping of cilia on the inner surface of the oviduct
  • Fertilisation occurs
• Vulva
• Ovary
  • Produce oestrogen and progesterone
  • One ovary releases a mature ovum into the oviduct every menstrual cycle
• Uterus
  • hollow organ where foetus develops
  • Fertilised ovum/embryo is implanted in the endomentrium
  • Smooth muscles of the uterine wall contrats during childbirth to expel the foetus
• Cervix
• Vagina

Menstrual Cycle Pregnancy

Advantage §

• Only one parent needed
• No fusion of sperm and ovum needed
• All beneficial qualities passed on to offspring
• Produces offspring faster than sexual reproduction
• Colonise existing habitat rapidly
• quickly populate favourable habitats

Sexual Reproduction w/ Single parent §

• Organisms can have both male and female sexual organs
• called hermaphrodites
• e.g. certain flowers

Advantages §

• Offspring may inherit beneficial qualities from both parents
• Variation in the offspring allows species to be better adapted to survive changes in the environment (fundamental to evolution)
• Survive changing environments

Comparison §

Property	Asexual Reproduction	Sexual Reproduction
Fusion of gametes	No	Yes
Genetically identical offspring	Yes	No
Relative speed	Quicker	Slower
Parents required	1	1 or 2