(i) glycogen and starch-both are carbohydrates and stored food products.v
(ii) chlorophyll and haemoglobin-both are pigments
(iii) gills and lungs-both are respiratory organs
(iv) arteries and veins-both are blood vessels

Rings of cartilage prevents the trachea from collapsing

If platelets are not present in the blood, then clotting at the site of injury will not take place. This will result in continuous bleeding and could be fatal for the organism.

Gastric glands in stomach release hydrochloric acid, enzyme pepsin and mucus. Mucus protects the inner lining of stomach from the action of hydrochloric acid and enzyme pepsin. If muscus is not released, it will lead to erosion of inner lining of stomach, leading to acidity and ulcers.

Cellulose forms the largest part of the herbivore's food. Digestion of cellulose takes longer time because the enzymes for its digestion are produced by the ruminant bacteria that live in the gut of the herbivores. Long length of the small intestine ensures that the food stays for a longer duration and proper digestion is possible. In the case of carnivores, cellulose is not present in the diet, thus the length of the small intestine is smaller.

(i) Aim: To show the action of saliva on the food we eat.
Materials Required: Starch solution, test tubes, iodine solutions, saliva and dropper.
Procedure
Take 1 mL starch solution in two test tubes marked as A and B.
Now, add 1 mL saliva to test tube A only and leave both test tubes undisturbed for 20-30 min.
After 30 min add few drops of dilute iodine solution in both the test tubes. And observe the change.
Observation In test tube B, the solution turns into blue black colour whereas in test tube A, the solution remains the same.
Conclusion The iodine solution gives blue colour in the presence of starch, but here in test tube A saliva was also present, which contains starch digesting enzyme amylase. Due to addition of saliva, the starch breaks down into glucose. Therefore, the blue colour does not show in test tube A.
(ii) Large fat globules are broken down into small uniformly distributed fat particles by the action of bile salts present in bile juice. This is called emulsification of fat. This facilitates the action of pancreatic enzymes.

The different constituents of blood are plasma (the fluid part of the bloo(d) and blood corpuscles consisting of RBCs, WBCs, and platelets)
WBCs are known as the soldiers of the body because they fight against the pathogenes that invade our body, thus preventing the occurence of diseases.

(i) Oxygen enters the human body through the nasal passage and reaches the lungs.
(ii) Numerous alveoli are present in the lungs. These alveoli are surrounded by many blood capillaries. From the alveoli, 0₂ is taken up by the red blood cells present in the blood capillaries.
(iii) Similarly, the CO₂ from the various tissues is transported to the alveoli.
(iv) This CO₂ is then released through the nasal passage during exhalation. Alveoli are the sites of exchange of gases. Each lung contains 300- 350 million alveoli.
These alveoli increase the surface area for gaseous exchange, making the process of respiration more efficient.

(i) Ventricles have to pump blood out of the heart into various organs of the body, therefore they have thicker muscular walls than atria.
(ii) Plants do not move and have a large proportion of dead cells in many tissues. As a result, plants have low energy needs and therefore transport system in plants is slow.
(iii) Circulation of blood in aquatic vertebrates such as fishes differs from that in terrestrial vertebrates as fishes have two-chambered heart. The blood is pumped to the gills for oxygenation and is then transported to the rest of the body.
On the other hand, most terrestrial vertebrates have lungs for oxygenation of blood. The deoxygenated blood is transported to heart from where it is transported to lungs for oxygenation and is then distributed to all body parts.
(iv) During daytime, due to transpiration pull, more water is absorbed by roots that is why absorption is faster in daytime.
(v) Veins have valves whereas arteries do not because valves have to prevents the back flow of blood as blood flows in them at low pressure.

The two ways in which glucose is oxidized to provide energy in diverse organisms are listed below.
1. Aerobic respiration
2. Anaerobic respiration
Aerobic respiration : It occurs in the presence of oxygen, respiration occurs, and the products are carbon dioxide, energy, and water.
Glucose + Oxygen \(\rightarrow\) Carbon dioxide + Water + Energy
- \(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(\mathrm{l})+6 \mathrm{O}_2(\mathrm{~g}) \rightarrow 6 \mathrm{CO}_2(\mathrm{~g})+6 \mathrm{H}_2 \mathrm{O}(\mathrm{l})+\) Energy
Anaerobic respiration - It occurs in the absence of oxygen, respiration occurs, and the products generated are lactic acid or ethanol and energy.
Glucose \(\rightarrow\) Alcohol + Carbon dioxide + Energy
Glucose \(\rightarrow\) Lactic acid + Energy
- \(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(\mathrm{l}) \rightarrow 2 \mathrm{C}_3 \mathrm{H}_6 \mathrm{O}_3(\mathrm{l})+\) Energy

Differences between Aerobic and Anaerobic respiration: