DAV Class 8 Science Solution Chapter 14 Reproduction in Animals
DAV School Books Class 8 Science Solution Chapter 14 Reproduction in Animals all Question Answer. DAV Class 8 14th Chapter Reproduction in Animals full Chapter explanation by expert teacher.
DAV School Books Class 8 Science Solution Chapter 14 Reproduction in Animals
A.) Fill in the blanks.
1.) Genetically identical individuals are produced by ___________ reproduction.
2.) ___________ are the specialised cells that take part in sexual reproduction.
3.) An animal, that produces both male and female gametes, is known as a ___________ animal.
4.) A fertilised egg is also known as the ___________.
5.) The incubation period for a hen’s egg is ___________.
Answer: (1) Asexual (2) Gametes (3) Hermaphrodite (4) Zygote (5) 21 days
B.) Match the following.
1. Hydra | (a) hermaphrodite |
2. Reptiles | (b) calcite |
3. Earthworm | (c) budding |
4. Gills
5. Egg shell |
(d) oviparous
(e) tadpole |
Answer: (1) C, (2) D, (3) A, (4) E, (5) B
C.) Tick the correct option.
1.) The site of fertilisation, in humans, is the-
Answer: oviduct
2.) The reason, why parrot does not belong to the same group as that of monkey, man, cat, is that-
Answer: it is oviparous.
3.)Answer: Yeast
4.) A caterpillar develops into a silk moth through the process of-
Answer: metamorphosis
5.) A foetus can be best defined as-
Answer: a well-developed embryo.
D.) Answer the following questions in brief.
1.) Distinguish between asexual and sexual reproduction.
Answer: The merging of male and female gametes from two separate parents occurs during sexual reproduction. It entails the transfer of genetic data between the two parents and can produce children that exhibit features from both parents in combination. Internal and external fertilisation are two examples of sexual reproduction.
2.) How is reproduction carried out in Hydra?
Answer: Asexual reproduction is the main method of reproduction for hydra. This process of the parent Hydra creating a bud that later develops into the a new Hydra linked to the parent is known as “budding.” When this budding has matured has matured enough it separates itself from the body and lives as a separate living being.
3.) How is fertilisation in a hen different from fertilisation in a frog?
Answer:In order to fertilise an egg inside a hen’s reproductive system, sperm must first enter the hen’s body. This process is known as internal fertilisation. Fertilization in frogs occurs externally, which means the sperm and egg connect outside the body, typically in water.
4.) State the difference between oviparous and viviparous animals.
Answer: Eggs laid by oviparous animals hatch apart from the mother’s body. Live young are born to viviparous animals, and they grow inside their mothers’ bodies.
5.) Why is the number of eggs, laid by frogs at a time, much higher than those laid by a hen?
Answer:Since frogs are amphibians and utilise external fertilisation to reproduce, while hens are birds and then use internal fertilisation to breed, frogs lay a far higher amount of eggs than hens. Frogs must lay more eggs because they place their eggs externally in order to maximise the likelihood of fertilisation. Hens, in contrast, only produce one or two eggs at once because internal fertilisation increases the likelihood of fertilisation.
6.) How will you differentiate between a zygote and an embryo?
Answer: A zygote is the fertilised egg that results from the union of an egg and a sperm cell; it is the first stage of the development of a new organism. It is a single-celled organism that possesses all the genetic material required to develop into a person. The developmental stage that comes after the zygote stage is called an embryo. It is a multicellular organism that can start to resemble a human being since its tissues and cells have started to differentiate.
7.) It is the mother who gives birth to a child. How do children, then, get features. of both the parents?
Answer: Genetic inheritance is the process by which children inherit traits from both of their parents. Each child inherits a distinct set of traits thanks to the interaction of their parents’ genes.
E.) Answer the following questions.
1.) Define the term ‘Metamorphosis’. List the changes that a tadpole undergoes to develop into a frog.
Answer: The process of metamorphosis is when an organism undergoes a change in its form or nature, such as when a caterpillar turns into a butterfly or a tadpole turns into a frog. Most creatures go through metamorphosis, a natural occurrence of growth and development, in order to attain adulthood. The female frog lays an egg, which the male frog fertilises in the water to create the tadpole. The tadpole’s tail starts to get shorter as it gets bigger, and its body starts to get legs. Its gills and fins start to disappear at the same moment. The tadpole eventually develops four legs, loses its tail, and has a more parched and scaly skin. The development of lungs and the ability to dwell on land mark the tadpole’s final stage of transformation. Now that it has reached adulthood, the frog can hop, jump, and swim.
2.) Trace the sequence of events that lead to development of a chick from the fertilised egg of a hen.
Answer: The embryo starts to form and the egg begins to internally rotate after around 18 days. The embryo will begin to form its internal organs, including the heart and digestive system. The embryo will also start to develop bone and feather follicles at this phase. The embryo will keep growing and developing over the coming days until it is prepared to hatch. The egg will begin to swing back and forth as the hatchling prepares to break out of its shell with its egg tooth. When a chick hatches, its down feathers begin to puff up, and it begins to walk and attempt to eat for the first time.
3.) Where does fertilisation occur in human beings? How does the zygote formed eventually develop into an infant?
Answer: Fertilization occurs in the Fallopian tubes of female humans. After fertilisation, the resulting zygote travels through the tubes and attaches to the uterus. After then, it continues to grow and divide into numerous cells, eventually developing into an embryo. The embryo is then placed within the uterine wall, where it develops for the duration of the pregnancy. As the pregnancy progresses, the embryo will develop into a foetus and finally an infant.
4.) Draw a neat well labelled diagram of the human sperm. Also, write how its shape and size help it in its functioning?
Answer: Sperm’s dimensions and shape enable faster and more efficient swimming, which supports its function. The sperm can move quickly through the female reproductive system due to its pointed head. Because the sperm’s body is tapered, it may easily turn and manoeuvre within the female reproductive system. The sperm’s propulsion to travel in the area of the egg comes from its whip-like tail. Since larger sperm have more energy and are therefore more inclined to reach the egg, the size of the sperm as a whole is also important.
5.) Draw a neat and well labelled diagram of (i) the reproductive system of the human female (ii) the male reproductive system.
Answer:
(1) diagram of the reproductive system of the human female
(2) Diagram of the male reproductive system.
6.) Write the function(s) of each of the following parts of the human female reproductive system:
(a) Ovaries
Answer: Under favourable circumstances, the ovaries generate an egg that is later fertilised by the sperm.
(b) Oviduct
Answer: The location of fertilisation is the oviduct.
(c) Uterus
Answer: The uterus is where the embryo implants and develops into the foetus.
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