Life’s Internal Secrets
Q1. Fill in the blanks.
1. ________________ artery takes the blood to the lungs for oxygenation. (Pulmonary)
2. ______________ is the largest gland in the body. (Liver)
3. The digested food is absorbed by the __________ in the small intestine. (Villi)
4. Lymph flows in ____________ direction. (one)
Q2. Correct the following statements.
1. Aquatic animals breathe at a slower rate than the terrestrial animals.
Ans. Aquatic animals breathe faster than terrestrial animals.
2. In human beings the blood goes to the heart in one cycle once.
Ans. In human beings the blood goes to the heart twice during each cycle of circulation.
3. Plasma is called as tissue fluid.
Ans. Lymph is called as the tissue fluid.
4. Carbohydrates are the body building nutrients.
Ans. Carbohydrates are the energy giving nutrients.
5. Calcium oxalate crystals present in the cells of some plants are called as resins.
Ans. Calcium oxalate crystals present in the cells of some plants are called as raphides.
Q3. Give scientific reasons.
1. Breathing rate increases during vigorous exercising.
Ans.
i. During vigorous exercise, the demand for oxygen increases due to increased energy production.
ii. Therefore, breathing rate increases to provide more oxygen.
2. Translocation is needed in all higher plants.
Ans.
i. Transport of nutrients from leaves to other parts of the plant is termed translocation.
ii. It is needed in all higher plants because every part of the plant needs food for harnessing energy and for building and maintaining the organism.
3. The plants are kept in dark before determining the factors essential for photosynthesis.
Ans.
i. When the plants are kept in dark all the starch stored in them gets used up and no new starch is produced.
ii. Such destarched plants help to determine the factors essential for photosynthesis.
4. It is necessary to separate oxygenated blood from the deoxygenated blood in mammals.
Ans.
i. Mammals have high energy needs since they constantly use energy to maintain their body temperature.
ii. It is necessary to separate oxygenated blood from deoxygenated blood in mammals because such separation allows a high efficient supply of oxygen to the body required for high energy production.
Q4. Draw a well labeled diagram of the following.
1. Human excretory system.
2. Vertical section of the human heart.
3. Digestive glands.
Q5. Answer the following.
1. How are fats digested in the human body?
Ans.
i. Whenever food enters the small intestine, the bile and pancreatic juice enter there through a common duct.
ii. Bile makes the food alkaline and breaks the large fat globules into smaller ones.
iii. The enzyme lipase in the pancreatic juice breaks down the fats.
iv. Various intestinal juices secreted by the walls of the small intestine complete the digestion of fat converting it into fatty acids.
2. What would be the consequences of deficiency of haemoglobin in the human body?
Ans.
i. Haemoglobin in the blood performs a very important function of absorbing and carrying oxygen from lungs to the body tissues and CO2 from body tissues to the lungs.
ii. Therefore, due to the deficiency of haemoglobin, the body tissues do not get sufficient oxygen which leads to a state called anaemia.
iii. Fatigue, palpitation, dizziness, headache, nausea, lack of concentration etc., are some of the symptoms of anaemia.
3. How do plants get rid of their excretory products?
Ans.
i. Gaseous excretory materials are eliminated by diffusion.
ii. Waste products stored in the vacuoles of the leaves, flowers, fruits and bark are removed by the periodical shedding of these parts.
iii. Some waste products are stored as resins and gum in old xylem. When the trunks of these trees are cut, these substances ooze out.
iv. Plants also excrete some waste substances into the soil around them.
Q6. Given below are the end products of different reactions involving glucose.
Write the reaction number in front of the following:
1. Anaerobic reaction =
2. Reaction in human muscles =
3. Aerobic respiration =
4. Reaction in plant cells =
5. Reaction in liver =
Ans.
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
Q7. Answer briefly:
1. Explain the process of translocation in plants.
Ans.
i. Transport of nutrients from leaves to other parts of the plant is called translocation.
ii. It takes place through phloem in upward as well as downward direction.
iii. This process needs energy which is obtained from ATP.
iv. When food materials like sucrose are transferred to phloem tissue, using ATP, the concentration of water molecules decreases in that area.
v. This results in the movement of water into the cells due to osmosis.
vi. The increased contents within the cells exert a high amount of pressure on their wall.
vii. This pressure moves the food materials to the adjacent cells with low pressure.
viii. This allows the phloem to move material according to the plant’s needs.
2. Explain the structure and function of a nephron.
Ans.
i. The basic filtration unit in the kidney is a cluster of thin walled blood capillaries called as nephron.
ii. Each nephron has a cup shaped thin walled upper and called Bowman’s capsule which contains a bundle of blood capillaries called glomerulus.
iii. When blood containing urea enters the glomerulus it gets filtered through glomerular capillaries.
iv. The selectively permeable wall of the Bowman’s capsule allows the water molecules and small molecules of the other substances to pass through them and forms glomerular filtrate.
v. The blood, free from these materials is taken to the heart through the renal vein.
vi. The glomerular filtrate collected in the Bowman’s capsule further passes through the nephron tubule where reabsorption of water and useful molecules take place.
vii. The remaining fluid containing the waste forms the urine which eventually enters a long tube called the ureter.
viii. It is further stored in the urinary bladder and from there it is thrown out through the urethra.