A - True ribs, B - Sternum, C . False ribs, D - Floating ribs

Rheumatic fever is an autoimmune disease which occurs 2-4 weeks after throat infection usually a streptococcal infection. The antibodies developed to combat the infection cause damage to the heart. Effects include fibrous nodules on the mitral valve, fibrosis of the connective tissue and accumulation of fluid in the pericardial cavity.

Hypertension is the most common circulatory disease. The normal blood pressure in man is 120/80 mm Hg. In cases when the diastolic pressure exceeds 90 mm Hg and the systolic pressure exceeds 150 mm Hg persistently, the condition is called hypertension. Uncontrolled hypertension may damage the heart, brain, and kidneys.

All Vertebrates have notochord during embryonic development. Later it is replaced by the vertebral column. But in lower chordates like prochordates, vertebral column is not present.
They have only notochord in the adult or larval stage. Hence it is said that all vertebrates are chordates but all chordates do not have vertebrate characters.

Ctenophores are exclusively marine. They emit light. It helps the animals in finding food, mate and escape from the predators.

Scientists have discovered a new and unusual species of frog in the Western Ghats mountain range in India.
The frog has shiny, purple skin. The scientists have called the new species as Bhupathy's purple frog, in honour of their colleague Dr. Subramaniam Bhupathy, a respected herpetologist who lost his life in the Western Ghats in 2014.

(i) Extremophiles are capable of synthesizing their food without sunlight and oxygen by utilizing hydrogen sulphide and other chemicals from the volcanic vents.
(ii) Methanogens produced methane.
(iii) Halophiles live in salty environments and thermoacidophiles thrive in acidic environments and high temperatures.

Five kingdom classification defined by R.H. Whittaker as Monera, Protista, Fungi, Plantae, and Animalia based on the cell structure, mode of nutrition, mode of reproduction and phylogenetic relationships.

The main criteria of systematics is identifying, describing, naming, arranging, preserving and documenting the organisms. Apart from the above said features, evolutionary history of the species and the environmental adaptations and interrelationship between species are also being investigated in systematics.

The key characters of living organisms are, cellular organization, nutrition, respiration, metabolism, growth, response to stimuli, movement, reproduction, excretion, adaptation, and homeostasis.

The presence of a large number of species in a particular ecosystem is called "Biological diversity" or in short 'Bio-diversity'.

a) Pivot joint
b) Gliding joint
c) Ball and Socket joint
d) Hinge joint

(i) It is a large opening which lies at the posterior base of the skull.
(ii) Medulla oblongata of the hind brain descends down the spinal cord through the foramen magnum.

1. Healthy lungs contain large amounts of elastic connective tissue around the alveoli, containing elastin, which makes the lung tissue elastic.
2. People with emphysema and bronchitis have difficulty in exhaling because the enzyme elastase destroys the elastin around the alveoli and reduces the elasticity of the lungs.

1. Mucus membrane lining the airway contains goblet cells which. secrete mucus a slimy material rich in glycoprotein
2. Microorganisms and dust particles attach in the mucus films and are carried upwards to pass down the gullet during normal swallowing.

1. During hard physical work, we require more energy.
2. The metabolism of food increases. This increases the amount of CO₂ in the blood.
3. The increase of CO₂ concentration in the blood stimulates the respiratory centre of the brain.
4. The brain sends stimulus through nerves for the increase in the rate of respiration. Thus we breathe faster during any kind of hard physical work.

\(I\frac { 2 }{ 2 } ,C\frac { 1 }{ 1 } ,PM\frac { 0 }{ 0 } ,M\frac { 2 }{ 2 } \times 2=20\)

Enzymes like trypsin, pepsin etc can act on proteins of the tissue lining the digestive tract if food is not available for digestion. Hence they are produced in an inactive form and are activated when food enters the alimentary canal. Salivary amylase is not found in inactive form since it breaks starch. Starch is not a component of tissues.

The average life span of RBC is about 120 days after which they are destroyed in the spleen which is called the graveyard of RBC

Albumin: Maintains the osmotic pressure of the blood.
Globulin: Transports molecules such as oxygen and carbon dioxide.

1. Earthworms have their most important organ in the first 20 segments.
2. If earthworm gets cut after the 20th segment, the anterior half can regenerate, while the posterior half shall disintegrate after some time.

The functions of epithelium include protection, absorption, filtration, excretion, secretion and sensory reception

Skeletal muscle, Smooth muscle and Cardiac muscle