Do animals reproduce? How is it possible?. The animals reproduce: a. asexually b. sexually c. like...
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Transcript of Do animals reproduce? How is it possible?. The animals reproduce: a. asexually b. sexually c. like...
![Page 1: Do animals reproduce? How is it possible?. The animals reproduce: a. asexually b. sexually c. like the plants d. a and b are correct d. a and b are correct.](https://reader038.fdocuments.in/reader038/viewer/2022110211/56649ee15503460f94bf14a6/html5/thumbnails/1.jpg)
Do animals reproduce? How is it possible?
![Page 2: Do animals reproduce? How is it possible?. The animals reproduce: a. asexually b. sexually c. like the plants d. a and b are correct d. a and b are correct.](https://reader038.fdocuments.in/reader038/viewer/2022110211/56649ee15503460f94bf14a6/html5/thumbnails/2.jpg)
The animals reproduce:a. asexually b. sexually
c. like the plantsd. a and b are correct
d. a and b are
correct
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REMEMBER: Animals reproduce asexually,
like: worms, starfish, seahorse and lower animals.
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But there are animals which reproduce sexually too.
![Page 5: Do animals reproduce? How is it possible?. The animals reproduce: a. asexually b. sexually c. like the plants d. a and b are correct d. a and b are correct.](https://reader038.fdocuments.in/reader038/viewer/2022110211/56649ee15503460f94bf14a6/html5/thumbnails/5.jpg)
If they reproduce sexually, they have some special characteristics
like:
* ________
* ________
* _______
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In sexual reproduction, two individuals produce offspring
that have genetic characteristics from both parents.
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Sexual reproduction introduces new gene combinations in a population through genetic
recombination.
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Gametes In animals, sexual reproduction encompasses the fusion of two distinct gametes (sex cells) to form a zygote.
They are:- egg-sperm
Zygote
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GAMETES: - The zygote is diploid (two sets of chromosomes)
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This genetic information is donated through a process called fertilization. There are two mechanisms:EXTERNAL
INTERNAL
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It is external when the eggs are fertilized outside of the body.
External
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External fertilization occurs mostly in wet environments and requires both the male and the female to release their gametes into their
surroundings (usually water)
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An advantage of external fertilization is that it results in the production of a large number of offspring
One disadvantage is that environmental hazards such as predators greatly reduce the chance of surviving into adulthood.
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Amphibians and fish are examples of animals that
reproduce this way.
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The second is internal (the eggs are fertilized within the female
reproductive tract).
INTERNAL
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Animals that use internal fertilization specialize in the protection of the developing egg. For example, reptiles and birds secrete eggs that are covered by a protective shell that is resistant to water loss and damage.
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Mammals protect using a step further by allowing the embryo to develop within the mother.
This extra protection increases the chances of survival because mom supplies everything that the embryo needs.
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Reproductive cyclesReproductive cycles in many vertebrates and invertebrates are related to changes in day length.Day length is a reliable indicator of season for timing circannual events such as reproductive behavior and migration.
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ACTIVITY
1. What are the main characteristics of sexual reproduction in animals?
2. Explain this sentence : “The zygote is diploid” What does it mean ?
3. Write some riddles which give examples of animals which reproduce by internal fertilization.
4.Do animals reproduce in any moment? Why?
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http://biology.about.com/od/basicgenetics/a/aa062708a.htm
http://biology.about.com/od/genetics/a/aa040805a.htm