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?
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
What are alloys?
The kidneys in human beings are a part of the system for
(a) nutrition. (c) excretion.
(b) respiration. (d) transportation.
A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards south (b) towards east
(c) downward (d) upward
What is the role of decomposers in the ecosystem?
What does an electric circuit mean?
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Why does a compass needle get deflected when brought near a bar magnet?
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
If a woman is using a copper -T, will it help in protecting her from sexually transmitted diseases?