Arihant - Class X - Heredity and Evolution [ Chapter - 9 ]Contact Number: 9667591930 / 8527521718Arihant - Class X - Heredity and Evolution [ Chapter - 9 ]Contact Number: 9667591930 / 8527521718Parents transmit some of their characteristics into their offsprings. How?
Genes are the unit of inheritance, what makes them necessary for all organisms?
Inheritance/heredity is possible because of a certain factor present in organisms. What is this factor?
Reproduction leads to variation. How?
In any population, no two individuals are absolutely similar. Why?
A pair of contrasting characters behaves independently of each other. Which law of Mendel does this statement support?
What is the cause of variation in asexually reproducing organisms?
Give an example where sex is determined by environmental factors.
In human females, the gametes formed have X-chromosomes in all. Give reason.
Why is it that the unit of evolution is population, not the individual?
State one of the evolutionary forces leading to the origin of a new species according to the Darwin theory of evolution.
Give the respective scientific terms used for studying
(i) the mechanism by which variations are created and inherited and
(ii) the development of new types of organisms from the existing ones.
Write one word for the formation of new species due to gradual change over long period of time.
Vestigial organs are present in human body as the indication of evolution. Name a few such organs present in the body.
Which vestigial organ in man suggests that he is a descendent of herbivorous mammals?
Identify the method which uses carbon for studying fossils.
What is the evolutionary significance of the fossil Archaeopteryx?
Give an example of a characteristic being used to determine, what relationship do two species have in terms of evolution?
Barriers of different kinds in an area restricts the reproductive interactions between species. What are these barriers and what do they lead to?
Which type of organism will have more variations — sexually or asexually reproducing organisms?
Enumerate the functions of chromosomes.
In Mendel's experiment of inheritance in which he took two contrasting characters, i.e. round green and wrinkled yellow seeds,
(i) What was the phenotype of offsprings in F1-generation?
(ii) What was the ratio of offsprings in F2-generation?
Explain Mendel's observation when he crossed a homozygous tall (TT) plant with homozygous dwarf (tt) plant followed by self-cross.
An individual inherits different traits from his parents. On what basis classification of traits as dominant and recessive is done?
What are the key factors in the modem concept of evolution?
Summarise the modern synthetic theory of evolution.
What are connecting links? How do they provide us information about the evolution of an organism?
Our teeth and an elephant's tusks are homologous organs'. Justify this statement. What do the analogous organs indicate?
Two plants, A with white flowers and B with red flowers were crossed. The F1 progeny shows all red flowers and F2 has three red and one white. Categorise the trait as dominant and recessive.
In human beings, the statistical probability of getting either a male or female child is 50:50. Give a suitable explanation.
A chimpanzee can hold objects by its hand and an elephant by its trunk. Are these two organs analogous or homologous? Give reason in support of your answer.
A teacher was showing a video on different animals when Varun observed the similarities in sharks and dolphins about shape of body, fins and flippers. He classified both of them as homologous to each other. Is he right? Give reasons in support of your answer.
A child questioned his teacher that why do organisms resemble their parents more as compared to grandparents. In which way will the teacher explain to the child?
(i) In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of eyes of the persons having the following
combination of genes?
(a) Bb (b) bb (c) BB
(ii) What do you class this trait of eye colour in human? Explain.
In a pea plant, find the contrasting trait if
(i) the position of flower is terminal
(ii) the flower is white in colour
(iii) shape of pod is constricted
In a monohybrid cross, pink coloured flowers are dominant over white coloured flowers. If parent plants belong to pure breeding dominant trait and pure breeding recessive trait, what will be the phenotype or morphological feature of F1-generation? If F1 plants are self-fertilised, what would be the phenotypic ratio or how many dominant and recessive traits will be produced in the progeny? Explain with an illustration.
In pea plant, round seed is dominant over the wrinkled. If a cross is carried out between these two plants, give answer to the following questions.
(i) Mention the genes for the traits of parents.
(ii) State the trait of F1 hybrids.
(iii) Write the ratio of F2 progeny obtained from this cross. What is the name of the cross?
Can sexual reproduction lead to the variations in characters, speciation and evolution? Explain.
(i) If, we cut the tail of a mouse, will tail occur in the next generation of that mouse? Give reason to support your answer.
(ii) What are the features that Archaeopteryx had in common to the reptiles?
(i) 'Males are heterogametic'. Why?
(ii) Differentiate between inherited and acquired characters by giving two points.
Traits that are acquired during lifetime do not result in evolution. Why? Give atleast two examples to support your answer.
What is speciation? List four factors that could lead to speciation. Which of these cannot be a major factor in the speciation of a self-pollinating plant species? Give reason to justify your answer.
(i) What would happen if two groups of organisms of a single species never exchange genes?
(ii) In which way can the study of diverse forms of life be done effectively?
The two areas of study namely 'evolution' and 'classification' are interlinked. Justify the statement.
A scientist is conducting embryological studies for collecting evidences supporting evolution. Is he going the right way. Give reason in support of your answer.
(i) Give the evidence that the birds have evolved from reptiles.
(ii) Insects, Octopus, Planaria and vertebrates possess eyes. Can we group these animals together on the basis of eyes that they
possess? Justify, your answer giving reason.
How and why did human race spread from Africa to other parts of the world?
'A trait may be inherited, but may not be expressed'. Justify this statement with the help of suitable example.
Give reason for your choice.
A person first crossed pure-breed pea plants having round-yellow seeds with pure-breed pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F1-generation. When F1-generation pea plants having A-B type of seeds were cross-breed by self-pollination, then in addition to the original round yellow and wrinkled-green seeds, two new varieties A-D and C-B types of seeds were also obtained.
(i) What are A-B type of seeds?
(ii) State whether A and B are dominant traits or recessive traits.
(iii) What are A-D type of seeds?
(iv) What are C-B type of seeds?
(v) Out of A-8 and A-D types of seeds, which one will be produced in (a) minimum number and (b) maximum number in the F2 -generation?
Kalawati often blames her daughter-in-law for having only daughters and no son. Being a biology student, how will you convince Kalawati that her daughter-in-law has no role in giving birth to girls or boys?
Define evolution. How does it occur? Describe, how fossils provide us evidences in support of evolution.
Name any five vegetables generated from a common ancestor through artificial selection rather than natural selection. Also mention the features for which each vegetable is selected.
(i) Identify the fossils A, B and C.
(ii) In which region was fossil C found?
(iii) In which region are recent fossils found?
X, Y and Z are three animals. The animal X can fly, but animal Y can only run on ground or walls. The forelimbs of animals X and Y have the same basic design, but they are used for different purposes, such as flying and running, respectively. The animal Z became extinct a long time ago. The study of fossils of Z tells us that it had some features like those of X and some like those of Y. In fact, Z is said to form a connecting link in the evolutionary chain of X and Y.
(i) What would the animal Z be?
(ii) Name the animal groups to which X and Y belong.
(iii) What name is given to the forelimbs like those of X and y, which have the same basic design, but different functions?
(iv) Name one feature in which Z resembled X.
(v) Name one feature in which Z resembled Y.
(vi) Which is the correct evolutionary chain involving X, Y and Z X Y or Y Z X?
Why is it more appropriate to compare the process of evolution with branches of a tree rather than with a ladder?
Explain the original idea of tracing evolutionary relationships.
Identify analogous and homologous organs amongst the following.
Wings of an insect, wings of a bat, forelimbs of lizard, forelimbs of bird.
Out of potato, sweet potato, pea tendril and spinach, which two are
(i) homologous organs
(ii) analogous organs?
Why are thorn of Bougainvillea plant and a tendril of Passiflora plant considered as homologous structures?
Rohit's father is a wrestler and has a robust body. He was also awarded as Mr. India when he was young. Rohit is his only child. As Rohit grew older, everyone expected him to have the same body built as his father. But, he is thin. His friends tease him and he feels depressed by it.
(i) Is it true that a wrestler's son should also have heavy muscles?
(ii) What type of character is it; acquired or inherited?
(iii) What are the values shown by Rohit's Mends?
Anita had a huge scar on her cheek after she met with an accident during her school days. She is worried if her baby would inherit the scar she had acquired. Her doctor, a sincere medical practitioner explained that the scar is an acquired trait and successfully convinced Anita that she need not to worry about it.
Read the given passage and answer the following questions:
(i) What are acquired traits?
(ii) How is it different from inherited traits?
(iii) Mention the values of the doctor that shows in the passage.
Mita observed that her grandmother was preparing a family tree. On enquiring why it was done, she explained that it was necessary to know our roots as we have inherited many traits from our ancestors. She also mentioned that now everybody wants to live in a nuclear family and joint families have disappeared.
Read the given passage and answer the following questions:
(i) Human shows maximum similarity in evolutionary terms with which mammal?
(ii) Mita has hazel coloured eyes which match with her mother's eyes. Suggest a mason for this similarity in eye colour between Mita and
her mother.
(iii) What values do you think children would learn in a joint family?