Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin.
(d) Cytokinin
Cytokinin is a plant growth hormone also called phytohormones that promotes cell division (in shoot apical meristem or root apical meristem), morphogenesis (shoot & root initiation), chloroplast maturation and apical dominance (where main stem of the plant is dominant over side stem).
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?
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
What is the role of the split ring in an electric motor?
Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
Compare the power used in the 2 Ω resistor in each of the following circuits:
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
What is a good fuel?
How can three resistors of resistances 2 Ω, 3 Ω, and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm. (c) chloroplast.
(b) mitochondria. (d) nucleus.
Why does the sky appear dark instead of blue to an astronaut?
How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?