Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Sexual reproduction is a type of reproduction that involves the fusion of male and female gametes to produce a .
The male reproductive organs include a pair of testes, two sperm ducts, and a penis. The testes produce the male gametes called .
The female reproductive organs include a pair of ovaries, oviducts (fallopian tubes), and the uterus. The ovaries produce female gametes called (singular: ).
Fertilization is the process of the fusion of a with an . During this process, the nuclei of the sperm and the egg fuse to form a single nucleus.
Internal Fertilization occurs inside the female body (e.g., humans, cows, birds). External Fertilization occurs outside the female body, usually in water (e.g., , , ).
The fertilized egg is called a , which divides repeatedly to give rise to an .
Animals which give birth to young ones are called animals, while those which lay eggs are called animals.
The stage of the embryo in which all the body parts can be identified is called a .
📐Formulae
💡Examples
Problem 1:
In external fertilization, why do organisms like lay hundreds of eggs while a lays only one egg at a time?
Solution:
Organisms like practice external fertilization where the fusion of gametes occurs in water. Laying hundreds of eggs and releasing millions of sperm increases the mathematical probability of successful fertilization, as many eggs and sperm are carried away by water currents, wind, or eaten by predators.
Explanation:
Since the environment is uncontrolled, the high quantity of gametes ensures that at least a few survive to adulthood.
Problem 2:
Identify the chromosomal composition of the gametes and the resulting zygote in humans.
Solution:
In humans, the male gamete () carries either an or a chromosome ( or ). The female gamete () always carries an chromosome (). The will be (female) or (male).
Explanation:
The fusion of haploid () gametes restores the diploid () number of chromosomes in the .