Tissues
Describe the structure of cartilage and bone.
Cartilage : It is a solid but semi-rigid and flexible connective tissue. It has large, bluntly angular cartilage cells called chondriocytes. They occur in clusters of 2 or 3 in small spaces (lacunae) scattered in the matrix. The cartilage is bounded externally by a sheath called perichondrium.
Hyaline cartilage is found in tracheal and broncheal rings, fibro-cartilage is present in intervertebral discs and pubic symphysis, elastic cartilage is found in pinna, tip of nose and eustachin tube.
T.S. of Cartilage.
Bone : Bone is solid, rigid and strong connective tissue. Its matrix become hard due to the deposition of salts of calcium and phosphorus. Osteocytes or bone cells are present in irregular spaces—lacunae in the matrix, interconnected by fine canals called canaliculi. The matrix occurs as layers—the lamellae arranged in concentric rings around narrow longitudinal cavities called Haversian canals. These canal carries blood vessels and nerves.
The haversian canals are inter-connected by transverse channels called Volkman’s canals. The long bones have central cavity filled with bone marrow and is called marrow cavity. The bone marrow is formed of blood vessels, nerve fibres and adipose tissue. Blood cells are produced in bone marrow. The bone is bounded externally by a tough sheath called periosteum.
T.S. of bone.
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Where do the lipids and proteins constituting the cell membrane get synthesized?
How does an Amoeba obtain its food?
What is osmosis?
Carry out the following osmosis experiment:
Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) keep cup A empty
(b) put one teaspoon sugar in cup B
(c) put one teaspoon salt in cup C
(d) put one teaspoon sugar in boiled potato cup D.
Keep this setup for two hours. Then observe the four potato cups and answer the following :
(i) Explain why water gathers in the hollowed portion of B and C?
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
By which instrument you can see internal structure of onion peel cell?
Do different organisms have different types of basic building units ? Briefly explain.
To what the shape and size of cells are related to?
What constitute the basic building block of the cell?
Can you find out more names of some of the unicellular organisms and fungi, other than given in your book?
Name two single celled animals.
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