Outline a project which aims to find the dominant coat colour in dogs.
Dogs have different coats. In order to find dominant coat (hair) colour in dogs, select a pure- bred of male and female dog having black colour or pure- bred of male and female having brown colour. Cross the homozygous male BB and homozygous female bb, and then observe the coat colour in dog progeny (offspring). If all progeny have black colour, this means that black colour will be the dominant coat colour in dogs and if progeny will have brown colour then the brown colour will be dominant coat colour.
And, by making the punnett square of F1 generation, we will get Bb, Bb, Bb, Bb ,i.e, all progeny are showing the black colour. So, it is concluded that the dominant colour is black.
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
How is the sex of the child determined in human beings?
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
Calculate the number of electrons constituting one coulomb of charge.
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
What is an homologous series? Explain with an example.
Why is variation beneficial to the species but not necessarily for the individual?
Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be –
(a) 1:2 (b) 2:1 (c) 1:4 (d) 4:1
Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)
(a) mass (b) speed
(c) velocity (d) momentum
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
How is the equal genetic contribution of male and female parents ensured in the progeny?
Which part of the brain maintains posture and equilibrium of the body?
Show how you would connect three resistors, each of resistance 6 Ω, so that the combination has a resistance of (i) 9 Ω, (ii) 4 Ω.
Why does the Sun appear reddish early in the morning?
Define the unit of current.
In evolutionary terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.