4.7.2Additional lessons
Sexual Reproduction — IB Biology HL Revision Notes & Topical Questions
5 min read 5 parts Lesson 56 of 101
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Section 1 of 5Gametes and Fertilisation
Sperm
- Sperm Small, motile male gametes made in large numbers, each carrying a haploid nucleus with an acrosome and a tail for swimming.
Egg
- Egg A larger female gamete that is non-motile, with food reserves, and made in much smaller numbers.
External fertilisation
- External fertilisation Gametes are released into water where fusion occurs, typical of fish and amphibians, and requires moisture and many gametes.
Internal fertilisation
- Internal fertilisation Sperm are placed in the female's body, protecting the gametes from drying out and improving the chance of fusion.
Section 2 of 5Male System
Testis
- Testis Contains seminiferous tubules where sperm are made and interstitial cells that secrete testosterone.
Epididymis and vas deferens
- Epididymis and vas deferens Sperm mature and are stored in the epididymis, then travel along the vas deferens.
Seminal vesicles and prostate
- Seminal vesicles and prostate These glands add fluid containing fructose, alkali and enzymes, which nourish and protect sperm as semen.
Urethra and penis
- Urethra and penis The urethra carries semen out of the body, and the penis places it in the female tract.
Section 3 of 5Female System
Ovary
- Ovary Contains follicles in which eggs develop and secretes oestradiol and progesterone.
Oviduct
- Oviduct The egg is swept along by cilia, and fertilisation normally takes place here.
Uterus
- Uterus A muscular organ with a lining, the endometrium, where an embryo implants and develops.
Cervix and vagina
- Cervix and vagina The cervix is a ring of muscle closing the uterus, and the vagina receives sperm and forms the birth canal.
| Structure | Male | Female |
|---|---|---|
| Gamete producer | Testis | Ovary |
| Gamete transport | Vas deferens | Oviduct |
| Hormones | Testosterone | Oestradiol, progesterone |
Section 4 of 5Pathway of Sperm
1
Sperm are produced in the seminiferous tubules of the testis and mature in the epididymis.
2
At ejaculation they pass through the vas deferens and mix with fluids from the seminal vesicles and prostate.
3
Semen leaves through the urethra and is deposited in the vagina near the cervix.
4
Sperm swim through the uterus into an oviduct, where one may fertilise an egg.
Section 5 of 5Exam Checklist & Tips
4.7.2 – Key Points for the Exam
- Testis The male organ that produces sperm and testosterone.
- Ovary The female organ that produces eggs and sex hormones.
- Endometrium The lining of the uterus that thickens ready for implantation.
- Semen Fluid containing sperm and secretions from the male glands.
Common Mistakes
- Confusing the urethra with the ureter; the ureter carries urine from the kidney only.
- Saying fertilisation occurs in the uterus; it occurs in the oviduct.
- Stating that the prostate gland produces sperm.
- Mixing up the roles of testosterone and oestradiol.
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