How does the creation of variations in a species promote survival?
Variation is the only factor of evolution. Evolution is the gradual changes in some features or functions of the pre-existing species. Every individual organism varies in their size, shape, behaviour from other organisms. Variations in the environment ensure survival because when any organism adapts themselves according to the variations there will be long term survival for that species, those species will survive who will struggle for their existence. The organisms who live in unfavourable conditions have to do more efforts for survival and those who survive in the most drastic conditions will be the fittest survival organism also known as Natural selection theory.
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
Outline a project which aims to find the dominant coat colour in dogs.
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.
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.
What is an homologous series? Explain with an example.
Why is variation beneficial to the species but not necessarily for the individual?
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?
In the Modern Periodic Table, which are the metals among the first ten elements?
When does an electric short circuit occur?
Differentiate between metal and non-metal on the basis of their chemical properties.
Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
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.
What chemical process is used for obtaining a metal from its oxide?
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Find out about the traditional systems of water harvesting/management in your region.
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
The autotrophic mode of nutrition requires
(a) carbon dioxide and water. (c) sunlight.
(b) chlorophyll. (d) all of the above.