What is hydrotropism? Design an experiment to demonstrate this phenomenon.

Hydrotropism is the process in which the stimulus is directed for the movement of roots towards the water. The experiment to demonstrate this phenomenon is given below: - Plant a seedling in a vessel containing soil. Adjacent to the seedling put a porous pot containing water. Leave the set-up for a few days. It is observed that the roots of seedlings bend towards the source of water and do not grow straight. It confirms from the experiment that the parts of plant show hydrotropism as the roots of plant bend towards the porous pot of water.

How do nerve impulses travel in the body ? Explain.

Neuron is the structural and functional unit of nervous system. There are three important parts present in neuron, they are: cyton, dendrite, and axon. The nerve impulses transfer from one neuron to the dendrite of the other neuron by releasing a special chemical called a neurotransmitter. This molecule floats across the synapse and binds to a receptor on the next dendrite part of the neuron. Then from dendrite the impulses pass impulses from cyton and next to the axon, and it goes on.

Why is the use of iodised salt advisable ? Name the disease caused due to deficiency of iodine in our diet and state its one symptom.

Iodine is needed by the thyroid gland for the production of thyroxin hormone. It regulates fat, protein and carbohydrate metabolism in our body. If the quantity of iodine intake is less than required, then the neck will swell up due to the enlargement of the thyroid gland. Therefore, the iodized salt is advised. The disease caused due to deficiency of iodine in the diet is known as simple goitre. It occurs because of the underproduction of the thyroid hormones. An iodine deficiency can cause a long list of symptoms that range from mildly uncomfortable too severe to even dangerous. The main symptom of the disease is that the swelling of the neck due to enlargement of the thyroid gland present in the neck. A decrease in thyroid hormones can also lead to other adverse effects, such as dry skin, hair loss, fatigue, weight gain, and increased sensitivity to cold.

Name the hormones secreted by the following endocrine gland and specify one function of each: Thyroid

The thyroid gland is an endocrine gland located over the trachea and larynx in the neck region. It is a butterfly-shaped gland helps in the secretion of thyroxin hormone, triiodothyronine, and calcitonin hormone. These hormones regulate the basal metabolic rate and the calcium concentrations in the blood respectively. The pituitary gland help to control the thyroid gland.

Name the hormones secreted by the following endocrine glands and specify one function of each: (b) pituitary

The pituitary gland is a pea-sized endocrine gland attached to the base of the brain. It plays an important role in controlling the growth and development and the functioning of the other endocrine glands. The pituitary releases the growth hormone which stimulates growth, metabolism, cell reproduction, and cell regeneration in animals. The major hormones produced by the pituitary gland are: Adrenocorticotrophic hormone, Follicle-stimulating hormone, Luteinizing hormone, Growth hormone, Prolactin, Thyroid-stimulating hormone, Oxytocin, vasopressin.

Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.

Neuron is the structural and functional unit of nervous system. There are three important parts present in neuron, they are: Cyton, dendrite, and axon. The nerve impulses transfer from synaptic cleft of one neuron to the dendrite of the other neuron. Then from dendrite the impulses pass on the labelled part 'a' that is cyton and next to the labelled part 'b' that is axon . Later it reaches to the end point of the neuron.

Name one gustatory receptor and one olfactory receptor present in human beings.

Receptors are often categorised by the kinds of stimuli they are responsive to. Biological transducers that transform energy into electrical impulses from both external and internal environments are receptors. There are many slender taste receptor cells in a single taste bud, all grouped in a banana-like cluster pointing towards the gustatory pore. These receptors mainly provide taste, so the tongue is one of the gustatory receptors found in the human body. The olfactory receptor, is a protein capable of binding odour molecules that play a key role in the sense of smell. The mucus of the nasal cavity covers the cilia, facilitating olfactory receptors to detect and respond to odour molecules. So the nose is the olfactory receptors present in human beings.