3.19b F1 x F1 Cross

3:1 is the Prediction Ratio or the Monohybrid F2 Ratio

3.19a P1 x P1 Cross

3.18b Genotypes

3.18a Phenotypes

3.2 Fertilisation

Understand that fertilisation involves the fusion of a male and female gamete to produce a zygote that undergoes cell division and develops into an embryo

Adult male + Adult female

Diploid cells (2n) have complete set of chromosomes
In humans 2n = 46

Diploid cells divide (with meiosis) to create gametes with haploid set (n - ½ a set; 23 in humans)
Gametes in male - sperm
Gametes in female - egg

Fertilisation
Sexual reproduction
Cells are brought together - joined/fused together
Forms one cell (Chromosomes: n + n = 2n)

New cell has 46 chromosomes - Zygote
Combination of male and female chromosomes

Zygote goes through mitosis - Cells divide to give two cells
Both contain 46 chromosomes
All cells have 2n / diploid number of chromosomes

Sufficient cells -> creates embryo

3.9b Female Reproductive System

Uterus generally small (size of orange) before pregnancy

1. Ovary - Meiosis - produces gametes (eggs)
2. Oviducts - Carry eggs to uterus
- Location where fertilisation takes place (in green)
3. Wall of uterus (muscle) - stretches during pregnancy and contracts during childbirth
4. Lining of uterus - accepts and develops egg -> embryo -> child (placenta)
5. Cervix - entrance to uterus for sperm
6. Uterus space - place where embryo develops
7. Vagina - Collects sperm cells

3.9a Male Reproductive System

Recall the structure and function of the male and female reproductive systems

1. Bladder - Stores urine

2. Testis - Meiosis (produces gametes - sperm cells)

3. Epididymis - Stores sperm cells

4. Vas deferens - Carries sperm cells to penis (tube)

5. Prostate - adds 20/30% of volume of semen, contains sugars, alkali (neutralise acidic secretions within vagina)

6. Seminal Vesicles - 70% of semen, contains "
Sperm cells are combined with prostate and seminal vesicle secretions to create semen

7. Urethra - Takes semen down penis, also exit for urine

8. Penis - Carry sperm cells into vagina during sexual intercourse

3.12 Amniotic fluid

Understand how the developing embryo is protected by amniotic fluid

Surrounding embryo - Amniotic fluid

Protects embryo
Fluid (largely water)
- Cannot be compressed
- Absorbs pressure

Prevents damage to embryo

Source

3.11 Placenta

Describe the role of the placenta in the nutrition of the developing embryo

Uterus - water-filled environment (amniotic fluids)

Embryo can't digest, breathe or excrete

Placental structure:
- Umbilical cord
Blood vessels lead from embryo (via umbilical cord) to placenta

Source

Placenta grows out of embryo
Grows into wall of uterus

Glucose, amino acids, fats etc.
Travels through maternal blood vessel
Taken into embryo through placenta

Mother's blood -> placenta -> embryo's blood

Source

Efficiency
1. Large surface area
2. Thin barrier

CO2/Urea produced by embryo
Travels into mother via placenta