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Biology - The Reproductive System

Grade 10ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

The male reproductive system consists of the testes, which produce sperms and the hormone TestosteroneTestosterone. The sperms are stored and matured in the EpididymisEpididymis and travel through the Vas deferensVas \ deferens.

The female reproductive system includes the ovaries, which produce ova (eggs), OestrogenOestrogen, and ProgesteroneProgesterone. Fertilization typically occurs in the Fallopian tubeFallopian \ tube (Oviduct).

The menstrual cycle is a 28-day cycle divided into phases: Menstrual phase, Follicular phase, Ovulatory phase (at day 1414), and Luteal phase.

Fertilization is the fusion of a haploid sperm (nn) and a haploid ovum (nn) to form a diploid zygote (2n2n).

The placenta is a temporary organ that facilitates the exchange of nutrients, O2O_2, and CO2CO_2 between the mother and the foetus through DiffusionDiffusion. It also secretes ProgesteroneProgesterone to maintain pregnancy.

The gestation period in humans is approximately 280280 days or 99 months, ending with ParturitionParturition (childbirth) triggered by the hormone OxytocinOxytocin.

📐Formulae

n (Sperm)+n (Ovum)2n (Zygote)n \ (Sperm) + n \ (Ovum) \rightarrow 2n \ (Zygote)

Human Chromosome Count: 2n=46\text{Human Chromosome Count: } 2n = 46

Gestation Period3840 weeks\text{Gestation Period} \approx 38-40 \text{ weeks}

Ovulation Day=Total Cycle Days14\text{Ovulation Day} = \text{Total Cycle Days} - 14

💡Examples

Problem 1:

Calculate the number of chromosomes in a human zygote if the sperm cell contains 2323 chromosomes.

Solution:

The zygote will have 4646 chromosomes.

Explanation:

Since the sperm is a gamete, it is haploid (n=23n = 23). The ovum is also haploid (n=23n = 23). During fertilization, they fuse to form a diploid zygote: n+n=2nn + n = 2n, which is 23+23=4623 + 23 = 46.

Problem 2:

Name the gas exchanged from the foetal blood to the maternal blood across the placenta.

Solution:

CO2CO_2 (Carbon Dioxide)

Explanation:

The foetus produces CO2CO_2 as a metabolic waste product during cellular respiration. This gas diffuses across the placenta into the mother's bloodstream to be exhaled by her lungs.

Problem 3:

If a woman has a regular menstrual cycle of 2828 days, on which day is ovulation most likely to occur?

Solution:

Day 1414

Explanation:

Ovulation generally occurs 1414 days before the start of the next menstrual period. For a 2828-day cycle, 2814=1428 - 14 = 14.