hereditary and evolution
Answers
1. The transmission of characters from parent to their offsprings is known as heredity.
The study of heredity and variations is known as genetics.Clones are those organisms which are the carbon copies of one another.Variation in sexually reproducing organisms are caused due to the following factors like environment, crossing over and recombination of genes and mutation.The first study of inheritance was done by Gregor Mendel on garden pea.Paired condition of chromosomes is known as diploid.Unpaired condition of chromosomes is known as haploid.DNA (Deoxyribo Nucleic Acid), RNA (Ribo Nucleic Acid) is the genetic material in all organisms.
Evolution
It is the sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced.
A. The evidences of evolution are :
i. Homologous organs,
ii. Analogous organs, and
Fossils
B. Theories of Evolution
Jean Baptiste Lamarck gave the first theory of evolution.
Classification
Evolutions are of three types :-
(i) Convergent Evolution
(ii) Divergent Evolution, and
(iii) Parallel Evolution.
12. Fossils : The remains of dead plants or animals that lived in the remote past are known as fossils.
Various kinds of fossils are : Ammonite, Trilobite and Dinosaur.
13. Evolution by Stages : Evolution of complex organs have taken place bit-by-bit over generations.
For example eye, feathers of birds have evolved because of survival advantage of intermediate stages.
Thus changes in DNA during reproduction are the main cause of evolution.
14. Human Evolution : All have beings belong to single speceis Homo sapiens, although there were many races of humans.
They have originated in Africa, some ancestors left Africa and migrated to West Asia, Central Asia, Eurasia South Asia, East Asia, Indonesia, Australia, America, while others stayed there.
Excavating, time-dating, studying fossils, determining DNA Sequences have been used for studying human evolution.
May it will help you .
The variations arises by the process of reproduction can be inherited. These variations in the organisms increase the survival chances of the individuals. The sexually reproducing organisms have two copies of genes for the same trait. The trait that gets expressed is called the dominant trait and the other is called the recessive trait. Traits in one individual may be inherited separately, giving rise to new combinations of traits in the offspring of sexual reproduction. The sex determination is different in different species. In human beings, the sex of the child depends on whether the paternal chromosome is ‘X’ (for girls) or ‘Y’ (for r boys). The variations in the species contribute to the genetic drift. Any changes in the non-reproductive tissues caused due to environmental factors are not inheritable. The speciation occurs when variation is combined with geographical isolation. The classification of organism’s shows evolutionary relationships. The evolution of an organism can be studied not just by the living species but also by studying fossils. Complex organs may have evolved because of the survival advantage of even the intermediate stages. During the course of evolution, organs or features may have adapted to new functions for example, feathers are thought to have been initially evolved for warmth and later adapted for flight. The process of evolution cannot be said to ‘progress’ from ‘lower’ forms to ‘higher’ forms. Rather, evolution seems to have given rise to more complex body designs even while the simpler body designs continue to flourish. Study of the human evolution indicates that all of us belong to a single species that evolved in Africa and spread across the world.