What factors could lead to the rise of a new species?
Genetic drift, natural selection, genetic variation in population, mutation, speciation, reproductive isolation. These all factors could lead to the rise of a new population, i.e, show patterns of evolution in different ways.
Genetic Variation in the Population: A species may have many populations in different places. Population is involved in this not an individual because the individual can die suddenly, but the population will not die in the sudden way it will continue and lead to the generation of new species.
Genetic Drift: It is the chance of elimination of genes when the part of a population dies during the natural calamity or migrates due to any reason. Some of the population dies, but the remaining part of the population migrants when mates with same or different species may lead to rise of a genetic variability or rise of a new species.
Natural Selection: This theory is given by Darwin, which represented the struggle for existence or elimination of the unfit members. Some members of the population have special genes which are able to grow up or reproduce at the higher level and transfer their special genes to the next generation and so on. Genes of the some members who reproduce the offspring at the higher level will become the strongest element in the gene pool which leads to change in gene frequency of the population and the rise of the new species.
Mutation: Mutation is the major source of the variation. When mutation occurs in the genes the new phenotype produced by the genetic variations, and these variations can have some advantages or some disadvantages, that alters the gene pool. Or when variations occur in the positive way, it will give rise to the new species.
Speciation: When the environmental changes occur or the part of population migrates to the new place due to some variations, may lead to the rise of a new species. If the population becomes adapted and if its members have some genetic variations, i.e, adapted to the new environmental changes give rise to the new population. And, the origin of new species from the existing one with the new acquired characters is known as speciation.
Reproductive Isolation: It is the mechanism which checks the population of the two different species from interbreeding (that breed with the other species). In brief, it preserves the integrity of the species by checking hybridization, they ensure that the different species will not breed. It may, however, be the origin of new species that occurs by the accumulation of the genetic variation in the population leads to evolution. There are many isolating mechanisms which leads to the barrier of the interbreeding species including:- geographical isolation, genetic isolation, ecological isolation, incompatibility, hybrid sterility, hybrid breakdown etc.
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.
How do Mendel’s experiments show that traits may be dominant or recessive?
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?
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?
Suggest some approaches towards the conservation of forests.
In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
Give any two ways in which non-biodegradable substances would affect the environment.
What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?
Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.
How does chemical coordination take place in animals?
A solution of a substance 'X' is used for whitewashing.
(i) Name the substance 'X' and write its formula.
(ii) Write the reaction of the substance 'X' named in (i) above with water.
How much energy is given to each coulomb of charge passing through a 6 V battery?
What does one mean by exothermic and endothermic reactions? Give examples.
Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(b) NaOH + H2SO4 → Na2SO4 + H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + HCl