Very Short Answer Questions - 1 Mark

Q1. Which organisms are called primitive?

Ans. Primitive organisms are those which have ancient body design and have not changed very much with the passage of time.

Q2. Name the branch of science that deals with classification.

Ans. Taxonomy

Q3. What is biological classification?

Ans. The system of arrangement of different plants and animals in different groups on the basis of their similarities and differences is called biological classification.

Q4. Who was the first to classify animals according to their habitats?

Ans. Aristotle was the first one to classify animals according to whether they lived on land, in water or in air.

Q5. What is 'binomial nomenclature?

Ans. It is the system of naming in which the scientific name of an organism has two components, i.e. genus and species.

Q6. What is evolution?

Ans. The life forms that exist today have risen because of changes in their body design over a course of time to adapt themselves in the changing conditions. This is called evolution.

Q7. Who gave the idea of evolution for the first time in the book Origin of Species'?

Ans. Charles Darwin

Q8. What is a genus?

Ans. A genus is a group of related species

Q9. Which groups of organisms do not have a defined nucleus or organelles?

Ans. Monera

Q10. Name the largest animal on the planet.

Ans. Blue whale (30 metres)

Q11. Name the largest tree on the Earth.

Ans. Redwood (100 metres)

Q12. Which plant has life span of more than one thousand years?

Ans. Pine trees

Q13. What are the three aspects of systematics?

Ans. Identification, nomenclature and classification.

Q14. Name a coelenterate that occurs singly and is commonly found in freshwater ponds.

Ans. Hydra

Q15. Name the group of sessile animals

Ans. Porifera

Q16. Name an organism that possesses flagella.

Ans. Euglena

Q17. What are corals?

Ans. Corals are marine coelenterates that live in colonies firmly attached to rocks.

Q18. Name two marine solitary coelenterates.

Ans. Jelly fish and sea anemone.

Q19. Name the group of animals, which developed nervous system for the first time.

Ans. Coelenterates

Q20. In which sub-division does xylem possess vessels?

Ans. Angiosperms

Q21. Name the organism which has nervous system but no brain.

Ans. Hydra

Q22. Which plants are perennial, evergreen and woody?

Ans. Gymnosperms

Q23. Name the reproductive organs of gymnosperms.

Ans. Cone

Q24. Name free living and parasitic flatworms.

Ans. Free living: Planaria; Parasitic: Tapeworm and liver fluke.

Q25. What are hermaphrodites?

Ans. The animal that possess both male and female reproductive organ is called hermaphrodite, e.g., earthworm

Q26. Name the group of animals, which has primitive nervous system but with brain which is developed for the first time.

Ans. Platyhelminthes

Q27. Name the first group of animals with true coelom.

Ans. Annelida

Q28. Define metameric segmentation.

Ans. Metameric segmentation is a type of segmentation where external divisions correspond to internal divisions.

Q29. Name the cavity present in the coelenterates.

Ans. Coelenteron

Q30. What is haemocoel?

Ans. When a well-defined cavity is absent and the spaces present contain colourless blood, i.e.,
haemolymph, it is called haemocoel.

Q31. Give the names of two groups of animals that are haemocoelomate.

Ans. Molluscs and arthropods

Q32. What are the skeletal elements in sponges?

Ans. Needles called spicules and spongin fibres are the skeletal elements in sponges.

Q33. What are the excretory organs in flatworm?

Ans. Protonephridia or flame cells.

Q34. What are cnidoblasts?

Ans. The stinging cells present on the tentacles of coelenterates like Hydra, which inject hypnotoxin into the prey to hypnotise it.

Q35. What is the name given to the body cavity of nematodes?

Ans. Pseudocoel

Q36. Name a parasitic annelid.

Ans. Leech

Q37. What is polymorphism? Give an example.

Ans. The presence of more than two types of individuals in a colony which differ in their structure as well as function is called polymorphism. E.g., honey bees.

Q38. Name two phyla which have open circulation.

Ans. Mollusca and echinodermata

Q39. Name two phyla which have radial symmetry.

Ans. Echinodermata and coelenterata

Q40. Why do amphibians do not possess exoskeleton?

Ans. Amphibians do not possess exoskeleton as their skin is thin, moist and act as a respiratory organ.

Q41. Why do birds possess hollow bones?

Ans. To make their body light in weight so as to make flying easier.

Q42. In which phylum are pharyngeal gill slits present?

Ans. Phylum chordata

Q43. What do you mean by 'characteristics'?

Ans. Characteristics means a particular form or a particular function of any organism. For example, the presence of five fingers on each hand of a human being is a characteristic.