V. Answer very briefly:
1. Define taxonomy.
Answer: Taxonomy is the science of classification which makes the study of wide variety of organisms easier and helps us to understand the relationship among different group of animals.
2. What is nematocyst?
Answer: The tentacles of organism belonging to phylum coelenterata bear stinging cells called cnidoblast or nematocyst.
3. Why coelenterates are called diploblastic animals?
Answer: The body wall of coelenterates is diploblastic with two layers, namely outer ectoderm and inner endoderm separated by non-cellular jelly -like substance called mesoglea. Due to presence of two layers in body wall, they are said to be diploblastic animals.
4. List the respiratory organs of amphibians.
Answer: Respiration is through by gills, skin, buccopharynx and lungs.
5. How does locomotion take place in starfish?
Answer: Locomotion in starfish is affected by tube feet.
6. Are jellyfish and starfish similar to fishes? If no justify the answer
(i) Jelly fish is a coelenterate. Their bodies are made of calcium carbonate.
(ii) Starfish fish is an echinoderm.
(iii) Cat fish is a fish species.
(iv) Jelly fish and star fish are invertebrates.
(v) Fishes are vertebrates.
7. Why are frogs said to be amphibians?
Answer: They are the first vertebrates to live on land with dual adaptation to live in aquatic and land environments. This double life is expressed as amphibious.
VI. Answer briefly:
1. Give an account on phylum Annelida.
Answer: (i) These are bilaterally symmetrical, triploblastic, first true coelomate animals with organ-system grade of organization.
(ii) Body is externally divided into segments called metameres joined by ring like structures called annuli.
(iii) It is covered by moist thin cuticle.
(iv) Setae and parapodia are locomotor organs.
(v) Sexes may be separate or united (hermaphrodites), e.g- Nereis, Earthworm, Leech.
2. Differentiate between flat worms and round worms?
• They belong to Phylum Platyhelminthes.
• They are mostly parasitic.
• Mostly hermaphrodites.
• They are acoelomate organisms.
• The alimentary canal is absent or simple.
• Eg: Tape worm.
• They belong to Phylum Aschelminthes.
• Exist as free - living soil forms or as parasites.
• Sexual dimorphism is seen.
• They are pseudocoelomate organisms.
• The alimentary canal is a straight tube.
• Eg: Round worm.
3. Outline the flow charts of Phylum Chordata.
Flow chart of phylum Chordata:
4. List five characteristic features of fishes.
(i) Fishes are poikilothermic (cold-blooded), aquatic vertebrates with jaws.
(ii) The streamlined body is divisible into head, trunk and tail.
(iii) Locomotion is by paired and median fins.
(iv)The body has a covering of scales.
(v) Respiration is through gills.
(vi) The heart is two chambered with an auricle and a ventricle.
There are two main types of fishes.
(i) Cartilaginous fishes, with skeleton made of cartilages e.g. Sharks, Skates.
(ii) Bony fishes with skeleton made of bones e.g. Carps, Mullets.
5. Comment on the aquatic and terrestrial habits of amphibians.
Aquatic habits of amphibians:
(i) The larva of amphibians (tadpole) lives in water and breathes with gills.
(ii) External fertilization occurs in frog with water as a medium of fertilization.
(iii) The adult frog has webbed feet to swim in water.
(iv) The skin is moist and glandular which helps in Respiration.
Terrestrial habits of amphibians:
(i) The adults live on land and breathe through lungs. Bucco-pharynx also helps in Respiration.
(ii) The fore limbs are short and help to hop on land.
6. How are the limbs of the birds adapted for avian life?
Answer: (i) Forelimbs of birds are modified into wings with feathers for flight.
(ii) The hind limbs are adapted for walking perching or swimming.
VII. Answer in detail:
1. Describe the characteristic features of different Prochordates.
(i) The prochordates are considered as the forerunners of vertebrates.
(ii) Based on the nature of the notochord, prochordata is classified into subphylum Urochordata and subphylum Cephalochordata.
(i) Notochord is present only in the tail region of free-living larva.
(ii) Adults are sessile forms and mostly degenerate.
(iii) The body is covered with a tunic or test. E.g. Ascidian
(i) Cephalochordates are small fish like marine chordates with unpaired dorsal fins.
(ii) The notochord extends throughout the entire length of the body. E.g. Amphioxus
2. Give an account on phylum Arthropoda.
(i) Arthropoda is the largest phylum of the animal kingdom.
(ii) They are bilaterally symmetrical, triploblastic and coelomate animals.
(iii) The body is divisible into head, thorax and abdomen.
(iv) Each thorasic segment bears paired jointed legs.
(v) Exoskeleton is made of chitin and is shed periodically as the animal grows.
(vi) The casting off and regrowing of exoskeleton is called moulting.
(vii) Body cavity is filled with haemolymph (blood).
(viii) The blood does not flow in blood vessels and circulates throughout the body (open circulatory system)..
(ix) Respiration is through body surface, gills or tracheae (air tubes).
(x) Excretion occurs by malphigian tubules or green glands. Sexes are separate. E.g., Prawn, Crab, Cockroach, Millipedes, Centipede, Spider, Scorpion.
ACTIVITY - 1
Identify the following pictures of Arthropods