(i) Bony fishes belongs to osteichthyes.
(ii) Notochord is replaced by skeletal system.
(iii) Body is spindle shaped.
(iv) Skin is covered by ganoid, cycloid and ctenoid scales.
(v) 4 paired filamentous gills covered by operculum to perform respiration.
(vi) Air bladder is independent to gut or dependent to gut.
(vii) Heart is ventral and two chambered.
(viii) Mesonephric kidneys excrete NH₃.
(ix) Lateral line sense organs are well developed (choose any three features).

Probiotics	Pathogenic bacteria
Probiotic bacteria are beneficial.	Pathogenic bacteria are harmful.
Probiotic bacteria may be decomposers, photosynthetic and few may be pathogenic.	All are pathogenic and causing diseases.

1. Pacemaker is a medical device which uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart.
2. The primary purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's natural pacemaker is not fast enough, or because there is a block in the hearts electrical conducting system.

The action potential occurs in response to a threshold stimulus but does not occur at sub threshold stimuli. This is called all or none principle.

The optic nerves and the retinal blood vessels enter the eye slightly below the posterior pole, which is devoid of photo receptors, hence this region is called blind spot.

Acromegaly is due to excessive secretion of growth hormone in adults.
Symptoms of acromegaly are :
Over growth of hand bones, feet bones, jawbones malfunctioning of gonads, enlargement of viscera, tongue, lungs, heart, liver, spleen, and also endocrine glands like thyroid, adrenal etc.

(i) Hormones coordinate different physical, physiological, mental activities and maintain homeostasis.
(ii) Maintenance of constant internal environment of the body by the different coordinating system.

Peculiarity characters of ducks:
1. The body is fully covered with oily feathers.
2. They have a layer of fat under their skin which prevents it from getting wet.
3. They lay eggs at night or in the morning.
4. The ducks feed on rice bran, kitchen wastes, waste fishes and snails.

Advantages of artificial insemination are:
1. It increases the rate of conception.
2. It avoids genital diseases.
3. Semen can be collected from injured bulls which have desirable traits.
4. Superior animals located apart can be bred successfully.

1. Lac cut from the host plant is called stick lac.
2. The lac present on the twig is scraped and collected.
3. After grinding the unnecessary materials like dust and fine particles are removed.
4. The resultant lac is called seed lac.

1. Queen bee
2. Nuptial flight

Actin, myosin, meromyosin, tropomyosin and troponin.

Renin, aldosterone and ADH.

Renal artery supplies (arterial) oxygenated blood and renal vein carries out deoxygenated blood (venous) from kidneys.

(i) A thin elastic flap called epiglottis is found in the upper respiratory tract.
(ii) It prevents the food from entering into the larynx.
(iii) It avoids choking of food.

RBCs contain an enzyme carbonic anhydrase
(i) It catalyses the carbonic acid (H₂CO₃) which is unstable and breaks into HCO^-₃ and H⁺ ions.
(ii) This enzyme facilitates the reaction in both directions. They are

(i) In stomach digested food is incompletely formed so that cannot be absorbed.
(ii) Finger like projections called villi are not found in the wall of stomach.
(iii) The concentration gradient by active transport cannot be created in stomach.

S.No.	Mitral Valve	semilunar Valve
1.	Found between left atrium and left ventricle.	Found at the entry of pulmonary artery and aorta.
2.	Has two flaps or cusps.	Has three flaps or cusps.
3.	Appear as flaps.	Appear as half moon shaped.
4.	Prevents the backword flow of oxygenated blood from left ventricle to left atrium.	Prevents the backward flow of deoxygenated blood into right ventricle and oxygenated blood into left ventricle.
5.	Also called as bicuspid valve.	Also called as pulmonary or aortic valves.

(i) Four species of cockroachs destroy food and contaminate them with their offensive odour.
(ii) Their mere presence is a sign of unhygenic condition and they are also known as the carriers of many bacterial diseases.
Eg: The allergen of cockroach can cause asthma or hypersensitivity among the human beings.

(i) The dried solid excreta rich in urea released by pygidium of earthworms are earthworm casts or worm castings or worm pellets
(ii) They are released by anus due to the function of nephridia
(iii) Released worm castings increase the fertility of soil for plant growth
(iv) Worm castings are less released during rainy season

(i) Pseudo-stratified epithelial cells are columnar, but unequal in size. Although the epithelium is single layered yet it appears to be multi-layered because the nuclei lie at different levels in different cells.
(ii) Hence, it is also called pseudostratified epithelium and its functions are protection, secretion and absorption.
(iii) Ciliated forms line the trachea and the upper respiratory tract.
(iv) The non ciliated forms, line the epididymis, large ducts of a glands and tracts of male urethra

(i) The larva trochophore belongs to the phylum annelida.
(ii) In the class Polychaetae of phylum annelida the fertilization is internal and the development is indirect due to the presence of larva trochophore.

(i) The phylum platyhelminthes includes flatworms.
(ii) Flatworms are triploblastic and exhibit bilateral symmetry.
(iii) Their coelom is compactly packed with parenchyma tissues so they do not have coelom and are called as acoelomates.

(i) In the gastrula stage of embryo on the root of gastrocoel an archenteron is formed.
(ii) Archenteron develops chordodorsatis or notochord dorsally.
(iii) Its anterior end forms brain and posterior axis form spinal cord.
Eg: Hemichordates and chordates.

(i) Both the spongin and spicules are the components of exoskeleton of sponges.
(ii) A hard exoskeleton protects the animals from external environment.
(iii) Both the components are produced by scleroblasts.