Q: What gas is released during the process of photosynthesis? Which experiment would you conduct to prove it?
A: Oxygen is released during the process of photosynthesis. I will conduct hydrilla funnel experiment to prove that.
Aim: To prove that oxygen is produced during the photosynthesis.
Apparatus: Beaker with water, test tube, funnel, hydrilla twigs, match box.
Procedure: Arrange the apparatus as shown in figure.
Place some hydrilla twigs in a funnel and keep it a beaker containing water.
Invert a test tube full of water over the stem of the funnel.
Ensure that the level of water in the beaker is above the level of the stem of the inverted funnel.
Place the apparatus in the sun for at least 3 hours.
After sometime it is observed that gas bubbles come from the hydrilla plants and these are collected at the end of the test tube.
After sufficient gas is collected, test tube is taken out of the beaker carefully by closing with the thumb.
Observation: Test the gas in the test tube by inserting a glowing match stick which would burst into flames. This shows the presence of oxygen.
Result: This shows that oxygen is produced during photosynthesis.
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Q: Observe the experiment given below and answer the following questions.
a) Why should we keep this plant in a dark room for three days?
b) Why KOH is used in the above experiment?
c) What precaution should you take in this experiment?
d) What are the raw materials for photosynthesis?
A: a) To consume the carbohydrates which are already present in the leaves. Otherwise experiment does not give better results.
b) To absorb the CO2 present in the bottle.
c) The tip of the leaf should not touch the KOH.
d) Carbon dioxide, water, sunlight and chlorophyll are the raw materials for photosynthesis.
Q: What do you understand about cardiac cycle? Explain.
A: One contraction and one relaxation of atria ventricles is called one cardiac cycle.
The cardiac cycle includes an active phase Systole and resting phase the Diastole of atria and ventricles.
The contraction phase of the heart beat is called Systole and relaxation phase of heart beat is Diastole.
Blood from venacava and pulmonary veins enters the right and left atria respectively. Now the atria contract and force the blood to enter into the ventricles.
When the ventricles are filled with blood they start contracting and atria start relaxing. The aperture between the atria and ventricle is closed by valves on ventricular contraction due to pressure the blood moves into the aorta and pulmonary artery. Then we hear the sound of lub.
When the ventricle start relaxing the pressure in the ventricles is reduced. The
blood which has entered the arteries tries to come back into the ventricles. The valves which are present in the blood vessels are closed to prevent the backward
flow of blood into the ventricles. Now we can listen the heart sound of dub. Then atria come to normal state to contract again.
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Q: What experiment would you conduct to prove that heat is liberated during respiration?
A: I would conduct the following experiment to prove that heat is liberated during
respiration.
Aim: To prove that heat is liberated during respiration.
Apparatus: Germinating bazra seeds (sprouts), thermos flask, thermometer, rubber cork.
Procedure:
Take some germinating bazra seeds (sprouts) into a thermos flask.
Make a hole to the rubber cork and insert thermometer.
Arrange carefully that the bulb of the thermometer should dip in the sprouts.
Record the temperature for every 2 hours.
Observe it throughout the day.
Observation: Constant increase in the temperature is observed in the thermometer.
Germinating seeds respire rapidly and release heat. So, constant increase in the
temperature is observed.
Result: Hence it is proved that heat is liberated during respiration.
Q: ‘Human excretory system is a wonderful mechanism’. How do you support this comment?
A: 1. It is wonder that excretion takes place in the minute tubules of the kidney.
2. It is an excellent mechanism that each kidney is made of a million of nephrons.
3. It is very interesting that the re-absorption of material in the tubular part of nephrons indicates the intelligence of human body.
4. It is very amazing thing that if one kidney is damaged the another one takes the responsibility of total excretion.
5. I feel that the cooperation of vasopressin for the active function of kidneys is wonder.
Q: Observe the diagram given below and answer the following questions.
a) What does the part ‘B’ indicate?
b) What does the part ‘C’ indicate?
c) Which organs produce ova and pollen grains?
d) What are the floral parts that attract insects?
A: a) Sepals. b) Stigma. c) Gynoecium and androecium d) Petals.
Q: How can you justify the enteric nervous system as the second brain of the gut?
A: The enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of long tube of our gut or alimentary canal.
The neurons of the enteric nervous system enable us to feel the inner world of our gut and its contents.
Enteric nervous system contains mass of neural tissue filled with important neuro
trans meters.
This reveals that it thus much more than merely handle digestion or inflict the occasional nervous pang of hunger.
Enteric nervous system stimulates and coordinates the breaking down of food
absorbing nutrients and expelling of waste.
Thus equipped with its own reflexes and senses the second brain can control several gut functions often independently of the brain.
Several scientists also believe that the enteric nervous system is a way to complicated to have evolve only to make sure things move through and out of our
gut smoothly.
Hence we can justify that the enteric nervous system is the second brain of
the gut.
Q: Who will be responsible for sex determination in human? How do you justify? Explain with the help of a flow chart.
A: Males are responsible for sex determination of a human baby.
Males have XY chromosomes which determine sex.
Females have XX chromosomes which determine sex.
All the gametes produced by women will be with only X chromosome.
The gametes produced by man will be of two types one with X chromosome and
other with Y chromosome.
If the sperm carries X chromosome and fertilizes the ovum, the resultant baby will have XX condition. So the baby will be a Girl.
If the sperm carries Y chromosome and fertilizes the ovum, the resultant baby will have XY condition. So the baby will be a Boy.
Hence I can say that males are responsible for sex determination in human.
Q: Write about the plant growth hormones and their uses.
A: Abscisic Acid: Closing of stomata, seed dormancy
Auxins: Cell elongation and differentiation of shoots and roots
Cytokinins: Promote cell division, promotion of sprouting of lateral buds, delaying the ageing in leaves, opening of stomata.
Ethylene: Ripening of fruits.
Gibberellins: Germination of seeds and sprouting of buds, elongation of stem, stimulation of flowering , development of fruit, breaking the dormancy in seeds and
buds.
4th lesson question and answers kaavali