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Ncert Class 10 - science - Biology

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Long Answer-Class 10 -Science- Biology-Chapter 6 – Control and Coordination

 

Class 10 -Science-Long Answer- Biology-Chapter 6 – Control and CoordinationQ1. Explain the role of the  endocrine system in maintaining homeostasis in the human body. 

Answer:

The endocrine system plays a vital role in maintaining homeostasis, which is the stable internal environment necessary for the proper functioning of the body. Here’s how the endocrine system contributes to homeostasis:

 Regulation of Hormone Levels: The endocrine system secretes hormones into the bloodstream, which act as chemical messengers to regulate various physiological processes. For example, insulin and glucagon hormones produced by the pancreas help regulate blood glucose levels, ensuring they remain within a narrow range. Similarly, thyroid hormones regulate metabolism, while cortisol regulates stress responses.

 Feedback Mechanisms: The endocrine system utilizes feedback mechanisms to maintain balance. Negative feedback loops are common, where a change in a physiological parameter triggers hormone release to counteract that change and restore balance. For instance, when blood glucose levels rise after a meal, insulin is released to facilitate glucose uptake by cells, thereby reducing blood glucose levels. Conversely, if blood glucose levels drop too low, glucagon is released to stimulate the release of stored glucose into the bloodstream, raising blood glucose levels.

 Coordination with the Nervous System: While the nervous system responds rapidly to stimuli, the endocrine system provides slower but longer-lasting responses. These two systems often work together to regulate body functions. For example, during the “fight or flight” response, the nervous system triggers the rapid release of adrenaline (epinephrine) from the adrenal glands, enhancing alertness and increasing heart rate and blood pressure. Meanwhile, cortisol, another hormone released during stress, helps to maintain prolonged stress responses by mobilizing energy reserves.

 Maintenance of Fluid and Electrolyte Balance: Hormones such as aldosterone, produced by the adrenal glands, help regulate fluid and electrolyte balance by acting on the kidneys. Aldosterone promotes the reabsorption of sodium and water in the kidneys, helping to maintain blood pressure and electrolyte balance.

 Q2. Differentiate between nervous and hormonal control systems in humans.

 

Nervous Control System

Hormonal Control System

Rapid transmission through electrical impulses along neurons

Relatively slow transmission through the bloodstream carrying hormones

Utilizes neurons to transmit signals

Utilizes hormones secreted by endocrine glands

Effects are usually short-lived

Effects are often more prolonged

Primarily responds to external stimuli and rapid changes in the environment

Responds to internal stimuli and gradual changes in the body’s state

Controls muscle movements, sensory perception, and cognitive processes

Controls metabolism, growth and development, reproduction, and maintenance of internal balance (homeostasis)

 Q3 a)Name the hormone which is released into the blood when its sugar level rises. Explain the need of Chemical communication in multicellular organisms the organ which produces this hormone and its effect on blood sugar level. Also mention the digestive enzymes secreted by this organ with one function of each.

(b)Explain the need of Chemical communication in multicellular organisms.

Ans: (A)Cells require glucose in order to breathe. Maintaining a steady level of blood glucose concentration is crucial. The hormone know n as insulin, which is generated by Thea-cells, controls blood glucose levels. Multicellular organisms require cell-to- cell communication for optimal operation. For example, when your brain signals your muscles to contract, they have to. The pancreas generates sp-cells and insulin, which raise blood glucose levels. Additionally, it produces pancreatic amylase, a digesting enzyme.

(b)Cell-to-cell communication is essential for coordinating biological processes. Messages are transferred from signalling cells to receiving cells—also referred to as target cells—through this communication. Proteins and other signalling molecule s are in volved in this signalling. Other items that happen in our body due to cell

 Q4.  What are tropic movements? Describe different types of tropic movements.

Tropic Movement: The movements which are in a particular direction in relation to the stimulus are called tropic movements. Tropic movements happen as a result of growth of a plant part in a particular direction. There are four types of tropic movements.

(i) Geotropic movement: The growth in a plant part in response to the gravity is called geotropic movement. Roots usually show positive geotropic movement, i.e. they grow in the direction of the gravity. Stems usually show negative geotropic movement.

(ii) Phototropic Movement: The growth in a plant part in response to light is called phototropic movement. Stems usually show positive phototropic movement, while roots usually show negative phototropic movement. If a plant is kept in a container in which no sunlight reaches and a hole in the container allows some sunlight; the stem finally grows in the direction of the sunlight. This happens because of a higher rate of cell division in the part of stem which is away from the sunlight. As a result, the stem bends towards the light. The heightened rate of cell division is attained by increased secretion of the plant hormone auxin in which is away from sunlight.

 (iii)Hydrotropic Movement: When roots grow in the soil, they usually grow towards the nearest source of water. This shows a positive hydrotropic movement.

 (iv) Thigmotropism Movement: The growth in a plant part in response to touch is called thigmotropism movement. Such movements are seen in tendrils of climbers. The tendril grows in a way so as it can coil around a support. The differential rate of cell division in different parts of the tendril happens due to action of auxin.

 Q5. Give reasons:

a. Pituitary is often termed as a master endocrine gland.

b. Pancreas helps in digestion and also regulates blood sugar levels.

c. Adrenals are known as glands of emergency.

Ans. a. Pituitary is often called a master endocrine gland because it controls and coordinates the secretion of all the other endocrine glands.

 b. Pancreas secretes pancreatic juice as well as a hormone called insulin. Pancreatic juice helps in digestion whereas insulin regulates blood sugar levels.

c. Emergency hormone in our body is adrenaline. It helps in coping during emergencies as it is secreted directly into the blood and carried to different parts of the body as a result the heart beats faster, resulting in a supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to the contraction of muscles around small arteries in these organs. This diverts the blood to our skeletal muscles. The breathing rate also increases because of the contraction of the diaphragm and rib muscles. All these responses together enable the animal body to be ready to deal with the emergency situation.

 Q6. How do control and coordination in plants differ from that in animals?

Ans.

 

Control in Plants

Control in Animals

Plant hormones diffuse to the place of action

Animal hormones are carried in blood vessels

Plants depend on hormones for control and coordination

Animals depend on nerve impulses and hormones for control and coordination

Hormones in plants are not secreted by specialized glands

Hormones in animals are secreted by specialized glands

Movement in plants occurs through a change in the water content of the action cells

Movement in animals occurs through a change in the shape and arrangement of proteins in the muscle cells