Write a note on the following, giving suitable examples of each of them:
(a) Complete digestive system
(b) External fertilisation
(c) Regeneration
(d) Exoskeleton
Answers
Answered by
112
Bonjour!
(a) Complete digestive system : Digestive system is said to be complete when the alimentary canal is a complete tube extending from mouth at one end to anus on the other end of body. Mouth is the opening for the entry of food and anus is the opening for the exit of waste material. Hence there are two separate
openings for entry of food and exit of waste. Aschelminthes to chordates, all possess complete digestive system.
(b) External fertilisation : Fertilisation is the fusion of male and female gametes (sperms and ova).
Fertilisation is said to be external when fusion takes place outside the genital tract of female in the surrounding environment (like water). Sperms are the motile cells which swim towards the egg (ovum) and fertilise it resulting in the formation of a diploid zygote. This type of fertilisation is exhibited by ctenophores,
some molluscs, echinoderms and hemichordates.
(c) Regeneration : Regeneration is the ability of an organism to replace its lost or damaged body parts. The lost or damaged body parts are regenerated by multiplication of cells. However, it cannot be taken as a normal mode of reproduction because it usually occurs after an accident or injury which results in the damage and the organism regenerates that part to compensate the loss. Hydra, Planaria, Star fish show good power of regeneration.
(d) Exoskeleton : Exoskeleton is the external skeleton that supports and protects an animal’s body. The exoskeletons also provide the hardness to the body. Many animals have the protective exoskeletons. For example, corals, arthropods and molluscs. Corals have an exoskeleton of calcium carbonate, arthropods
have a chitinous exoskeleton and molluscs have an exoskeleton in the form of a calcareous shell. The internal body organs of animals are provided protection with the help of exoskeleton. Since exoskeletons are rigid, they present some limits to growth. The animal can shed the old exoskeleton and grow new one, it is called moulting (e.g., arthropods).
Hope this helps...:)
(a) Complete digestive system : Digestive system is said to be complete when the alimentary canal is a complete tube extending from mouth at one end to anus on the other end of body. Mouth is the opening for the entry of food and anus is the opening for the exit of waste material. Hence there are two separate
openings for entry of food and exit of waste. Aschelminthes to chordates, all possess complete digestive system.
(b) External fertilisation : Fertilisation is the fusion of male and female gametes (sperms and ova).
Fertilisation is said to be external when fusion takes place outside the genital tract of female in the surrounding environment (like water). Sperms are the motile cells which swim towards the egg (ovum) and fertilise it resulting in the formation of a diploid zygote. This type of fertilisation is exhibited by ctenophores,
some molluscs, echinoderms and hemichordates.
(c) Regeneration : Regeneration is the ability of an organism to replace its lost or damaged body parts. The lost or damaged body parts are regenerated by multiplication of cells. However, it cannot be taken as a normal mode of reproduction because it usually occurs after an accident or injury which results in the damage and the organism regenerates that part to compensate the loss. Hydra, Planaria, Star fish show good power of regeneration.
(d) Exoskeleton : Exoskeleton is the external skeleton that supports and protects an animal’s body. The exoskeletons also provide the hardness to the body. Many animals have the protective exoskeletons. For example, corals, arthropods and molluscs. Corals have an exoskeleton of calcium carbonate, arthropods
have a chitinous exoskeleton and molluscs have an exoskeleton in the form of a calcareous shell. The internal body organs of animals are provided protection with the help of exoskeleton. Since exoskeletons are rigid, they present some limits to growth. The animal can shed the old exoskeleton and grow new one, it is called moulting (e.g., arthropods).
Hope this helps...:)
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Answer :-
☆ A ) Complete digestive system :-
:- The six activities involved in this process are ingestion, motility, mechanical digestion, chemical digestion, absorption, and defecation
☆ B) External fertilization :-
:- is a male organism's sperm fertilizing a female organism's .... Salmon, cod, trout, and char are all examples of the fishes that externally fertilize.
☆ C ) Regeneration :-
:- In biology, regeneration is the process of renewal, restoration, and growth that ... All these strategies result in the re-establishment of appropriate tissue polarity, structure .....
☆ Exoskeleton :-
:- Chitin forms the exoskeleton in arthropods including insects, arachnids such as spiders, crustaceanssuch as crabs and lobsters, and in some fungi and bacteria. Calcium carbonates constitute the shells of molluscs, brachiopods, and some tube-building polychaete worms.
Answer :-
☆ A ) Complete digestive system :-
:- The six activities involved in this process are ingestion, motility, mechanical digestion, chemical digestion, absorption, and defecation
☆ B) External fertilization :-
:- is a male organism's sperm fertilizing a female organism's .... Salmon, cod, trout, and char are all examples of the fishes that externally fertilize.
☆ C ) Regeneration :-
:- In biology, regeneration is the process of renewal, restoration, and growth that ... All these strategies result in the re-establishment of appropriate tissue polarity, structure .....
☆ Exoskeleton :-
:- Chitin forms the exoskeleton in arthropods including insects, arachnids such as spiders, crustaceanssuch as crabs and lobsters, and in some fungi and bacteria. Calcium carbonates constitute the shells of molluscs, brachiopods, and some tube-building polychaete worms.
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