How do Mendel’s experiments show that traits may be dominant or recessive?
The allele which always expresses itself in the presence of contrasting allele is a dominant allele and which does not express itself in the presence of its contrasting dominant allele is known as recessive allele.
Mendel showed the traits dominant or recessive by the monohybrid cross which is shown by the law of dominance in pea plants, in which the allele is expressed itself is dominant or the unexpressed one is recessive. He crossed the homozygous tall pea plant with genotype TT to the homozygous dwarf pea plant with genotype tt. Then, the F1 (filial generation) is formed with the result of phenotype Tt where T shows the tallness, i.e, dominant or t shows the dwarfness which remain unexpressed, i.e, recessive. And when he crossed again, he found the 3:1 phenotypic ratio and 1:2:1 genotypic ratio in F2 generation.
Outline a project which aims to find the dominant coat colour in dogs.
How is the sex of the child determined in human beings?
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?
How do Mendel’s experiments show that traits are inherited independently?
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?
Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
Explain the terms analogous and homologous organs with examples.
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
How does the creation of variations in a species promote survival?
Why are traits acquired during the life-time of an individual not inherited?
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 difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
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?
Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.
Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity
What were the limitations of Newlands’ Law of Octaves?
Differentiate between metal and non-metal on the basis of their chemical properties.
Choose the correct option.
The magnetic field inside a long straight solenoid-carrying current
(a) is zero.
(b) decreases as we move towards its end.
(c) increases as we move towards its end.
(d) is the same at all points.
How are the alveoli designed to maximise the exchange of gases?
Find the focal length of a convex mirror whose radius of curvature is 32 cm.
Why are carbon and its compounds used as fuels for most applications?
Which element has
(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?
Why are some substances biodegradable and some non-biodegradable?