Meaning of Reproduction

Sexual Reproduction in Animals for Class 5 Science

Through this concept, the students will be introduced to the process of sexual reproduction in animals.

After reading the concept, students will be able to:

• Know what are oviparous animals and provide examples.
• Explain the difference between viviparous and oviparous animals.
• Enlist viviparous animal examples.
• Know what is a marsupial animal and the functions of a brood pouch.
• Know that animals that lay eggs are called oviparous animals.
• Understand what is hatching
• Label the parts of an egg.
• Explain the functions of the germinal disc.

Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Sexual Reproduction in Animals provided in PDF format.

 

What is Reproduction?

Reproduction is the process by which living beings produce young ones of their own kind called offspring.Animals are divided into two categories based on their modes of reproduction—

• Viviparous animals: Animals that give birth to young ones. Examples: Dog, cat, horse, leopard, lion, zebra, elephant, man, etc.

 

• Oviparous animals: Animals that reproduce by laying eggs. Examples: Frog, snake, hen, duck, butterfly, shark, etc.

 

Viviparous animals:

• These animals give birth to young ones.
• Viviparous animals are further divided into mammals and marsupials based on their characteristic features.

 

Features of viviparous animals:

• The body of viviparous animals is covered with hair.
• They use their lungs for breathing.
• Viviparous animals are complex organisms with well-developed brains.
• The process of reproduction includes a gestation period during which the babies develop inside their mothers’ womb for a specific period of time.
• Once the offspring are born, they are nurtured by their mothers till they become independent to survive.
• Both marsupials and mammals have mammary glands to feed milk to their young ones.

Examples : Mammals—Tiger, deer, monkey, rat, goat, sheep, etc.; Marsupials—Kangaroo, koala, opossum, etc.

Oviparous animals:

• Animals that reproduce by laying eggs are called egg-laying or oviparous animals.

Features of oviparous animals:

• The young ones grow inside the eggs of these animals.
• The embryo gets nourishment from the yolk and the albumen that help in its growth and development.
• The eggs are protected from the predators and provided the warmth of the body or the sun till the embryo matures, the egg hatches and the young ones come out.

Examples : Insects, birds, reptiles, fishes and amphibians lay eggs for reproduction.

Let us now look at how some common oviparous animals reproduce.

 

Reproduction in birds:

• All birds lay eggs.
• The birds build nests to lay eggs and sit on them to keep them warm.
• It takes 21 days for a chick to hatch.
• The parents feed and take care of their young ones till they are strong to fly.

 

Reproduction in fishes:

• A fish lays thousands of eggs at a time in the water.
• All these eggs released by a fish in the water is collectively called a spawn.
• Only a few hundred eggs mature into tiny baby fishes; the rest are eaten by bigger fishes.
• Fish eggs do not have shells but have a jelly-like protective covering.• Fish eggs do not have shells but have a jelly-like protective covering.

 

Reproduction in reptiles:

• The animals which creep on the ground are called reptiles.
• Reptiles like snakes, turtles, crocodiles lay eggs in the holes of the ground.
• Shells of reptile eggs are leathery and elastic-like, and for this reason, the eggs do not break when they are laid on the ground.
• The eggs get warmth from the sun.
• After laying the eggs, some mothers go away and never return and leave the eggs to hatch on their own. Therefore, many of these eggs are eaten by other animals.

 

Parts of an Egg:

Eggs are laid by oviparous animals. An egg after fertilisation contains the zygote that develops inside it and comes out as a young one once the egg hatches.

The parts of an egg are described below—

• Shell
1. The outer oval-shaped overing of the egg is called shell.
2. It is white in colour and is made up of calcium carbonate.
3. The eggshell is porous and helps in the exchange of gases.
• Egg membranes
1. These membranes are located immediately below the shell.
2. The egg membranes protect the contents of the shell from bacterial growth and help in moisture retention.
• Albumen
1. It is the transparent part that surrounds the egg yolk.
2. It constitutes over 50% of the total liquid weight of an egg.
3. The function of albumen is to provide nutrition (protein and fats) to the developing embryo for proper growth and development.
4. It also protects the growing embryo from external injury.
• Yolk
1. It is the yellow part located at the centre of an egg.
2. The embryo develops within the yolk.
3. It is rich in fats that are consumed by the embryo while growing.
• Germinal disc
1. The small white spot on the yolk where the genetic material is located is called the germinal disc.
• Chalaza
1. Chalaza is the membranous structure that attaches the yolk to the end of the eggshell.
2. It keeps the position of the yolk intact as it is necessary for the developing embryo.

 

 New Words:

 

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