Life’s Internal Secrets – Maharashtra Board Class 10 Solutions for Science and Technology

Life’s Internal Secrets – Maharashtra Board Class 10 Solutions for Science and Technology (English Medium)

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Solution 1:

1. Pulmonary artery takes the blood to the lungs for oxygenation.
2. Liver is the largest gland in the body.
3. The digested food is absorbed by the villi in the small intestine.
4. Lymph flows in only one direction.

Solution 2:

1. Aquatic animals breathe at a faster rate than the terrestrial animals.
2. In human beings, the blood goes to the heart in one cycle twice.
3. Lymph is called the tissue fluid.
4. Proteins are body-building nutrients.
5. Calcium oxalate crystals present in the cells of some plants are called raphides.

Solution 3.1:

1. Our body needs a constant supply of oxygen which is obtained through breathing. Oxidation of glucose takes place with this oxygen, and energy is released in the form of ATP.
2. During vigorous exercise, there is more need of energy, i.e. more ATP molecules, and so, more oxygen is needed for cellular respiration.
3. Hence, to cater this increased demand for oxygen, the breathing rate increases during vigorous exercise.

Solution 3.2:

1. Higher plants have different storage parts like roots, leaves, flowers, fruits, seeds etc.
2. The amino acids, sugar and starch are stored in fruits and seeds for future use.
3. This food has to be carried to different parts of the plant so as to carry out various metabolic activities.
4. For this purpose, translocation is needed in all higher plants.

Solution 3.3:

1. Plants produce carbohydrates during photosynthesis which are used for their growth and energy.
2. The unused carbohydrates are stored in the form of starch. This starch has to be used completely before performing any experiments related to photosynthesis.
3. When the plant is kept in the dark, it utilises this stored starch and becomes destarched.
4. The factors such as sunlight, carbon dioxide and chlorophyll which are essential for photosynthesis can be studied well with such a destarched plant.
5. Therefore, the plants are kept in dark before determining the factors essential for photosynthesis.

Solution 3.4:

1. Mammals have high energy needs to maintain a high body temperature. This energy is supplied through oxygen-rich blood. Hence, oxygenated and deoxygenated blood should not mix with each other.
2. In the mammalian heart, these two types of blood are separated by a muscular partition, the septum. Thus, they can have highly efficient supply of oxygen through oxygenated blood.
3. Therefore, it is necessary to separate oxygenated blood from deoxygenated blood in mammals.

Solution 4.1:

Solution 4.2:

Solution 4.3:

Solution 5.1:

1. Alkaline medium is needed for the digestion of fats. This alkalinity is brought about by the bile juice secreted by the liver and stored in the gall bladder.
2. When food enters the small intestine, the gall bladder releases bile into it by means of a duct. Thus, the food becomes alkaline and the bile breaks the larger fat globules into smaller ones which help in enzyme action.
3. Pancreatic juice which contains enzyme lipase breaks down fats.
4. Intestinal juices secreted by the walls of the small intestine convert fats into fatty acids. Thus, the digestion of fats is completed in the small intestine.

Solution 5.2:

1. Haemoglobin is a respiratory pigment which carries the respiratory gases O₂ and CO₂ from the air present in the alveoli.
2. Deficiency of haemoglobin causes anaemia which means less supply of oxygen to different tissues and cells in the body.
3. A person suffering from anaemia shows symptoms such as tiredness, lack of energy, mild headache etc.
4. Presence of haemoglobin is responsible for the rapid transport of oxygen from the lungs to the various parts of the body.

Solution 5.3:

Excretory products need to be eliminated from the plant body though there is no definite excretory system in plants. Therefore, the plants get rid of their excretory products in following ways:

1. Gaseous excretory materials are eliminated through diffusion.
2. Excretory products are stored in the vacuoles of the leaves, flowers and fruits. The plants get rid of these excretory products by periodical shedding of these plant parts.
3. Some waste products are stored as resins and gums in the old xylem.
4. In some plants, waste is excreted in the form of calcium oxalate crystals.
5. Some waste materials are secreted inside the soil, while some wastes are very useful to human beings, e.g. rubber, latex and essential oils like eucalyptus or sandalwood oil.

Solution 6:

1. Anaerobic reaction = 5
2. Reaction in human muscles = 4
3. Aerobic respiration = 3
4. Reaction in plant cells = 1
5. Reaction in liver = 2

Solution 7.1:

1. The xylem and phloem are specialised tissues which conduct water and food, respectively.
2. The process of translocation requires energy in the form of ATP to transport food in plants.
3. By using ATP, food materials like sucrose are transferred to the phloem tissue. As a result, the concentration of water molecules decreases in that area, and causes the movement of water into the cells by osmosis.
4. Adjacent cells have low pressure, so the food materials are moved into them. In this way, the phloem is allowed to move food according to the plant’s needs. Example: Sugar stored in stems and roots is translocated to the buds for blooming them into flowers during the flowering season.

Solution 7.2:

1. 1. 1. A nephron is a cluster of thin-walled blood capillaries. It is the basic filtration unit in the kidneys.
      2. Each nephron has a cup-shaped upper end called the Bowman’s capsule.
      3. It contains a bundle of blood capillaries called the glomerulus.

   

   4. In the glomerulus, blood is filtered through the capillaries.

2.  5. The wall of the Bowman’s capsule is selectively permeable. It allows water molecules  and    small  molecules of other        substances to pass through it. This forms the glomerular  filtrate.
3.  6. The glomerular filtrate further passes through the tubular portion of the nephron where reabsorption of water and             useful substances takes place.
4.  7. The remaining fluid containing the waste products form urine.