How does phototropism occur in plants?
Phototropism is the process of growth of an organism in response to light reaction or stimulus. It is mostly seen in plants, but can also observed on other organisms. There are two types of phototropism:-
Positive phototropism:- Growth of plant towards the direction of light is positive phototropism.
Negative phototropism:- When growth of a plant is away from light is negative phototropism.
Several signalling molecules helps the plants to determine the light stimulus, activates genes & change the hormones for the growth of plant (i.e, auxine). This hormone helps the plants to have elongated cells on the farthest side from the light stimulus.
Draw the structure of a neuron and explain its function.
Which signals will get disrupted in case of a spinal cord injury?
How does chemical coordination take place in animals?
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Why is the use of iodised salt advisable?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
How do we detect the smell of an agarbatti (incense stick)?
How do auxins promote the growth of a tendril around a support?
Which part of the brain maintains posture and equilibrium of the body?
How does our body respond when adrenaline is secreted into the blood?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
In the Modern Periodic Table, which are the metals among the first ten elements?
What are the components of the transport system in human beings? What are the functions of these components?
Can you suggest some changes in your school which would make it environment-friendly?
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
How has the traditional use of wind and water energy been modified for our convenience?
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.
(b) An electric generator works on the principle of electromagnetic induction.
(c) The field at the centre of a long circular coil carrying current will be parallel straight lines.
(d) A wire with a green insulation is usually the live wire of an electric supply.
How is a voltmeter connected in the circuit to measure the potential difference between two points?
Why does distilled water not conduct electricity, whereas rain water does?
What are the limitations of extracting energy from—
(a) the wind? (b) waves? (c) tides?