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?
Why is sodium kept immersed in kerosene oil?
Find the focal length of a lens of power – 2.0 D. What type of lens is this?
What determines the rate at which energy is delivered by a current?
A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?
What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?
How do Mendel’s experiments show that traits may be dominant or recessive?
Explain the nature of the covalent bond using the bond formation in CH3Cl.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?