Life Processes class 10th

                             6. Life Processes

                           Class 10th Science  

                           Shiva Valley School

                           

Question 1:  Describe the structure and functioning of nephrons.

Answer

Nephrons are the basic filtering units of kidneys. Each kidney possesses large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman's capsule, and a long renal tubule.

Structure of a nephron Functioning of a nephron:

The blood enters the kidney through the renal artery, which branches into many capillaries associated with glomerulus. The water and solute are transferred to the nephron at Bowman's capsule. In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine. The filtrate then moves down into the loop of Henle, where more water is absorbed. From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons. The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.

Question 2: What are the methods used by plants to get rid of excretory products?

Answer:

Plants can get rid of excess of water by transpiration. Waste materials may be stored in the cell vacucles or as gum and resin, especially in old xylem. It is also stored in the leaves that later fall off.

Question 3: How is the amount of urine produced regulated?

Answer:

 The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such diuretic hormone (ADH) also regulates the amount of urine produced.

     

 Question 1: The kidneys in human beings are a part of the system for 

(a) nutrition.

(b) respiration.

(c) excretion. 

(d) transportation.

Answer

(c) In human beings, the kidneys are a part of the system for excretion.

Question 2: The xylemn in plants are responsible

(a) transport of water.

(b) transport of food.

(c) transport of amino acids.

(d) transport of oxygen,

Answer

(a) In a plant, the xylem is responsible for transport of water.

Question 3: The autotrophic mode of nutrition requires

(a) carbon dioxide and water.

(b) chlorophyll

(c) sunlight.

(d) all of the above.

Answer

(d) The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and sunlight.

Question 4: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm.

(b) mitochondria.

(c) chloroplast

(d) nucleus Answer

(b) The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Question 5: How are fats digested in our bodies? Where does this process take place?

Answer

Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This is referred to as emulsification of fats. It takes place in the small intestine.

Question 6: What is the role of saliva in the digestion of food?

Answer

Saliva is secreted by the salivary glands, located under the tongue. It moistens the food for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar

Question 7: What are the necessary conditions for autotrophic nutrition and what are its by-products?

Answer

Autotrophic nutrition takes place through the process of photosynthesis Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O₂ are the by-products of photosynthesis.

Question 8: How are the alveoli designed to maximise the exchange of gases?

Answer

 The alveoli are the small balloon-like structures present in the lungs The walls of the alveoll consist of extensive network of blood vessels. Each lung contains 300-350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m² area. This large surface area makes the gaseous exchange more efficient.

Question 9: What would be the consequences of a deficiency of haemoglobin in our bodies? 

Answer

Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood. This can lead to deficiency of oxygen in the body cells. It can also lead to a disease called anaemia.

Question 10: Describe double circulation in human beings. Why is it necessary? 

Answer

The human heart is divided into four chambers the right atrium, the right ventricle, the left Flow of blood in the heart: atrium, and the left ventricle.The heart has superior and inferior vena cava, which carries de-oxygenated blood from the upper and lower regions of the body respectively and supplies this de-oxygenated blood to the right atrium of the heart.

Flow of blood in the human heart

The right atrium then contracts and passes the de-oxygenated blood to the right ventricle, through an auriculo-ventricular aperture. Then the right ventricle contracts and passes the de-oxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood becomes oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart. Then the left atrium contracts and through the auriculo-ventricular aperture, the oxygenated blood enters the left ventricle.

The blood passes to aorta from the left ventricle. The acrta gives rise to many arteries that. distribute the oxygenated blood to all the regions of the body.

Schematic diagram of blood circulation in humans Therefore, the blood goes twice through the heart. This is known as double circulation. Importance of double circulation:

The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings.

As we know, warm-blooded animals have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O₂ for more respiration so that they can produce. more energy to maintain their body temperature. Thus, the circulatory system of humans is more efficient because of the double circulatory heart.

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