What is meant by analogous organs? Taking a suitable example, explain how they support the theory of Organic Evolution.
Analogous organs are those organs which I have different basic structural design and developmental origin but have similar appearance and perform similar functions.
Example: The wings of birds and bats look similar but have different design in their structure. They have a common function of flying but their origins are not common. So, birds and bats are not closely related.
In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.
Give an example of characteristics being used to determine how close two species am in evolutionary terms ?
What evidence do we have for the origin of life from inanimate matter (lifeless matter) ?
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]
a) Name the scientist who gave the laws of inheritance.
(b) Name an animal in which individuals can change sex. What does this indicate ?
(a) State one advantage of variation to a species.
(b) What are sex chromosomes ? How many sex chromosomes are there ? Name them.
Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.
What do you understand by the double helical structure of DNA? Who proposed this structure?
The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer. [All India(C)]
(a) What is the genotype of dwarf plants which always produced dwarf offspring ?
(b) What is the genotype of tall plants which always produced tall offspring ?
(c) What is the genotype of
(a) Why did Mendel choose pea plants for conducting his experiments on inheritance ?
(b) State Mendel’s second law of inheritance.
What name is given to the sequence of gradual changes over millions of years in which new species are produced ?
Write the names of at least three inorganic molecules which helped in the origin of life on the earth.
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
If we cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F2 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F2 generation but appeared in F2 generation, mentioning the reason for the same. [All India]
What type of plants were used by Mendel for conducting his experiments on inheritance ?
In the F2 generation of a cross, progeny having different traits are produced in the ratio 3:1. State whether it is a monohybrid cross or a dihybrid cross ? Give one example of such a cross.
Does genetic combination of mother play a significant role in determining the sex of a new born baby ?
(a)What is meant by ‘heredity’ ? What are the units of heredity.
(b) State Mendel’s first law of inheritance.
Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria ? Explain your answer.
(a) Define ‘natural selection’.
(b) “Only variations that confer an advantage to an individual organism will survive in a population”. Do you agree with this statement ? Give reason for your answer.
A man with blood group A marries a woman with blood 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 ?
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Why or why not ?
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement ? Why or why not ?
Distinguish between acquired and inherited traits by giving one example of each. Why are traits acquired during the lifetime of an individual not inherited? [Delhi(C)]
If the 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 ?
Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) Genes always work in …………………
(b) In pea plants, the gene for dwarfness is………………… whereas that for tallness is…………………
(c) Most people have………………… earlobes but some have………………… earlobes.
(d) A human gamete contains………………… chromosomes whereas a normal body cell has………………… chromosomes in it.
(e) All races of man have………………… blood groups.
(f) The………………… chromosomes for a………………… are XX whereas that for a………………… are XY.
Give an example of characteristics being used to determine how close two species are in evolutionary terms.
Study the following cross and showing self-pollination in Flf fill in the blank and answer the question that follows
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 ?
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?
During which stage can the chromosomes be seen clearly? Write the features of the eukaryotic and prokaryotic chromosomes.