NCERT Class X Science Class: Chapter –6. Life Processer – Part-14

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Question 80:

Explain the three pathways of breakdown in living organisms.

Answer:

Fate of Pyruvic Acid: The breakdown of pyruvic acid takes place in mitochondria and the molecules formed depend on the type of respiration in a particular organism. Respiration is of two types, viz. aerobic respiration and anaerobic respiration.

Anaerobic Respiration: This type of respiration happens in the presence of oxygen. Pyruvic acid is converted into carbon dioxide. Energy is released and water molecule is also formed at the end of this process.

Aerobic Respiration: This type of respiration happens in the absence of oxygen. Pyruvic acid is either converted into ethyl alcohol or lactic acid. Ethyl alcohol is usually formed in case of anaerobic respiration in microbes; like yeast or bacteria. Lactic acid is formed in some microbes as well as in the muscle cells.

Question 81:

Describe the flow of blood through the heart of human beings.

Answer:

The carbon dioxide rich blood has to rich the lung for the carbon dioxide to be removed. The oxygen rich blood is then pumped to the rest of the body. It comes from the lungs from the left atrium. It relaxes when it is collecting blood. It then contract when the left ventricle expands. So that blood is transported to it. When the muscular left ventricle contacts the blood is pumped out to the body.

Deoxygenated blood come from the body to the upper chamber on the right atrium. As the atrium contacts the right ventricle which in terms pump it to the lungs for oxygenation.

Image Figure shown the human heart

Image Figure Shown the Human Heart

Image Figure shown the human heart

Question 82:

Describe the process of urine formation in kidneys.

Answer:

Image the basic steps in urine formation

Image the Basic Steps in Urine Formation

Image the basic steps in urine formation

Each kidney contains over 1 million tiny structures called nephrons. Each nephron has a glomerulus, the site of blood filtration. The glomerulus is a network of capillaries surrounded by a cuplike structure, the glomerular capsule (or Bowman’s capsule). As blood flows through the glomerulus, blood pressure pushes water and solutes from the capillaries into the capsule through a filtration membrane. This glomerular filtration begins the urine formation process.

Inside the glomerulus, blood pressure pushes fluid from capillaries into the glomerular capsule through a specialized layer of cells. This layer, the filtration membrane, allows water and small solutes to pass but blocks blood cells and large proteins. Those components remain in the bloodstream. The filtrate (the fluid that has passed through the membrane) flows from the glomerular capsule further into the nephron.

The glomerulus filters water and small solutes out of the bloodstream. The resulting filtrate contains waste, but also other substances the body needs: essential ions, glucose, amino acids, and smaller proteins. When the filtrate exits the glomerulus, it flows into a duct in the nephron called the renal tubule. As it moves, the needed substances and some water are reabsorbed through the tube wall into adjacent capillaries. This reabsorption of vital nutrients from the filtrate is the second step in urine creation.

The filtrate absorbed in the glomerulus flows through the renal tubule, where nutrients and water are reabsorbed into capillaries. At the same time, waste ions and hydrogen ions pass from the capillaries into the renal tubule. This process is called secretion. The secreted ions combine with the remaining filtrate and become urine. The urine flows out of the nephron tubule into a collecting duct. It passes out of the kidney through the renal pelvis, into the ureter, and down to the bladder.

The nephrons of the kidneys process blood and create urine through a process of filtration, reabsorption, and secretion. Urine is about 95% water and 5% waste products. Nitrogenous wastes excreted in urine include urea, creatinine, ammonia, and uric acid. Ions such as sodium, potassium, hydrogen, and calcium are also excreted