CBSE Important Questions for Heredity and Evolution Class 10
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a. One Marks Questions
b. Short Answer type
c. Long answer questions
Very Short Answer Type Questions
Question 1.
What is speciation? Answer
It is the development of one or more species from an existing species.
Question 2.
What are genes and where they are located? Answer
Genes are part of DNA containing genetical details of the body, they are located in the chromosomes.
Question 3.
An organ like a wing in birds is an advantage to the organism. Did they appear in different stages or were formed due to single sudden change in them? Answer
No, wings of birds didn't appear suddenly. They were gradually evolved through different stages.
Question 4.
What happens when a dead insect is caught in hot mud? Give two points? Answer
Higher temperature of hot mud will speedup the decomposition process. So, insect buried under hot mud will not be well preserved but is decomposed.
Question 5.
If it said that, ‘there is no real progress in the idea of evolution, then what evolution is’? Explain. Answer Question 6.
Who is the father of Genetics? Answer
Johann Mendel
Question 7.
Write the scientific name of men and garden pea? Answer
The scientific name of men is Homo Sapiens and the Scientific name of the garden pea is Pisum Sativum.
Question 8.
What conclusion was drawn by Mendel after obtaining F2 progeny in a dihybrid cross? Answer
Mendel's dihybrid cross experiment laid the foundation for understanding the independent assortment of genes, leading to the second law of inheritance, known as Mendel's Law of Independent Assortment. It emphasizes the independent inheritance of two different traits in the same organism, contributing to the complexity and diversity of genetic traits.
Question 9.
What is the study of fossils known as? Answer
paleontology
Question 10. Identification of human races was done by a particular trait. Name the trait? Answer
skin color
Short Answer Type Questions
Question 11.
Explain what happen when in a group of organism, if organisms are not able to survive in changing environmental conditions?
Question 12. Explain the two ways by which individuals with a particular trait may increase n a population?
Question 13. What is the outcome of genetic drift between two sub. Populations.
Question 14. Sometimes, accidentally a dead body or its part get buried under depositing sediments and are preserved. These are fossils. How can the estimation of the age of fossils be done?
Question 15. Why are wings of butterfly ad wings of bat considered analogous? Give reason.
Question 16. What is the significance of variation?
Question 17. What is natural selection? Answer
Natural selection is a fundamental process in evolution by which organisms that are better adapted to their environment tend to survive and reproduce more successfully than those less well adapted. It is often described as "survival of the fittest." Key Components of Natural Selection
Variation: Within any given population, individuals exhibit variations in traits such as size, color, shape, or behavior. These variations are often genetically determined.
Inheritance: Some of these variations are heritable, meaning they can be passed on from parents to offspring through genes.
Differential Survival and Reproduction: In a particular environment, some variations may confer an advantage in terms of survival or reproduction. Individuals with these advantageous traits are more likely to survive and reproduce.
Adaptation: Over generations, the advantageous traits become more common within the population, leading to adaptations that enhance the population's overall fitness in that environment.
Question 18. What are dominant and recessive traits? Answer Dominant Traits
A dominant trait is a characteristic that is expressed in an organism even if only one copy of the dominant allele (gene variant) is present. In other words, if an individual inherits one dominant allele from one parent and one recessive allele from the other parent, the dominant trait will be expressed.
Example: In pea plants, the allele for tall stems (T) is dominant over the allele for short stems (t). A plant with one tall allele and one short allele (Tt) will have a tall stem.
Recessive Traits
A recessive trait is a characteristic that is expressed only when two copies of the recessive allele are present. If an individual has one dominant allele and one recessive allele, the dominant trait will be expressed, and the recessive trait will be hidden.
Example: In the same pea plants, the short stem trait is recessive, so a plant must have two short alleles (tt) to have a short stem.
Question 19.
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?
Question 20.
Why did Mendel select pea plant for conducting his experiment on inheritance?
Question 21.
The sex of the children is determined by what they inherit from their father and not their mother. Justify.
Question 22. What are acquired characters? Give example. Answer
Acquired characters refer to traits or characteristics that an organism develops during its lifetime as a result of environmental influences or personal experiences
It alters phenotype only,It is not transmitted to the next generation.It is a result of organisms respond to environmental challenges.
Example: muscular body
Question 23. Explain the terms analogous and homologous organs with examples? Answer
Question 24. How gene is responsible for controlling a trait? Explain by giving an example.
Question 25. Define Genetics. Answer
Genetics is the branch of biology that studies genes, genetic variation, and heredity in organisms. It seeks to understand how traits are passed from parents to offspring and how they are expressed in the individual.
Genes: Genes are segments of DNA that contain the instructions for producing proteins, which carry out various functions in the body. They are the fundamental units of heredity.
Heredity: Heredity refers to the process by which traits are passed from parents to their offspring through genes
Genetic Variation: Genetic variation is the differences in genes among individuals within a population. It is essential for evolution as it provides the raw material for natural selection.
Long Answer type Questions
Question 1
“The sex of a newborn individual in some species is largely determined genetically while in other it is otherwise.” Give three different examples to justify this statement? Answer
(a)In animals like lizard, the temperature at which fertilized eggs are kept determines whether the developing animal in the egg is male or female.
(b) In some animals like the snail, an individual can change sex.under different stress and environmental conditions.
(c) In Humans, the sex of the new born is decided by chromosome inherited from Father, if it is X , the new born is girl and if it is Y,the new born is boy
Question 2
If evolution is not equated with progress and further it is slow and gradual process then what could be the progressive trend in evolution? Explain giving a example. Answer
Evolution is the process by which organisms change over successive generations through variations in traits, natural selection, and other mechanisms. It is essential to recognize that evolution is not inherently directional or goal-oriented. It does not aim for "progress" or "improvement" in a general sense.
However, evolution can lead to increased complexity or specialization in certain lineages, depending on environmental pressures and opportunities. This can sometimes be interpreted as a "progressive trend," but it's essential to understand that these changes are not universally better—just better suited to specific environments or circumstances.
One example of a progressive trend in evolution might be the development of the mammalian brain, particularly in primates.Over millions of years, the brains of primates have become more complex, allowing for advanced cognitive functions such as problem-solving, communication, and social interaction.
Question 3
How is the equal genetic contribution of male and female parents ensured in the progeny? Question 4
What evidence do we have for the origin of life from inanimate matter? Question 5
Do genetic combinations of mother play a significant role in determining the sex of new born? Question 6
“Variation is beneficial to the species, but not necessarily for the individual”. Give reason. Question 7
“It is possible that a trait is inherited but may not be expressed.” Give a suitable example to justify this statement. Question 8
(a) Write the evidence o the basis of which it is concluded that birds have evolved from reptiles?
(b) Insects, Octopus, Planaria and Vertebrates also possess eyes. Can these animals be grouped together o the basis of the eyes they possess? Why or why not? Give reason to justify your answer. Question 9
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists I 60%of the same population? Which is likely to have arisen earlier? Question 10
List thee factors that provide evidences in favour of evolution in organisms & state the role of each in brief? Question 11
List in tabular form distinguishing features between acquired traits and inherited traits with one example of each? Answer
Characters that are passed on from parents to offspring are inherited characters e.g., colour of seeds, colour of eyes.
Characters appearing in an individual’s life time but cannot betransmitted to next generation are acquired characters e.g., obese body, loss of a finger in an accident
Question 12
A blue flower plant denoted by BB is crossed with that of white coloured flower plant denoted by bb.
(a)State the colour of flower you would expect in their F1 generation plants.
(b)What must be the percentage of white flower plants in F2 generation if flower of F1 plants are self – pollinated?
(c)State the expected ratio of the genotypes BB in the F2 progeny? Question 13 Define the term ‘evolution’. “Evolution should not be equated with progress”? Give reason to justify this statement. Question 14
How can a pure breed be represented symbolically? Explain by taking the example of purple and white flowers? Question 15
How do Mendel’s experiments show that traits are inherited independently? Depict with the help of example. Question 16
Mendel made two different types of cross monohybrid and dihybrid. Why did he obtain different type of ratios in his experiments? Question 17
Charles Darwin came up with the idea of evolution of species by natural selection. How Gregor Mendel’s experiments support Drawin’s view? Question 18
In a population of red beetles, living o green bushes, is being eater by crows. During sexual reproduction, a green beetle is found in progeny:
(a)What is the future of new trait?
(b)Will it survive in the new habitat?
Question 19
How do variations affect the evolution of those organisms that reproduce sexually? Question 20
Evolutionary relationship can be traced by study of homologons organ. Explain. Question 21
Natural selection of traits is different from artificial selection. Differentiate between the two by giving three points? Question 22
When is a recessive trait capable of expressing itself? Write its expression with respect to height of plant (genotype)? Question 23
How do Mendel’s experiments show that the
(a)traits may be dominant or recessive?
(b)traits are inherited independently? Question 24
What are fossils? How are they formed? Describe in brief two methods of determining the age of fossils. State any one role of fossils in the study of the process of evolution. Question 25
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. Question 26
How is the sex of the child determined in human beings? Question 27
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 explain? Question 28
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- bold A or O is dominant? Why or why not? Question 29
What is the probability of a girl or a boy being born in a family? Justify your answer. Answer
There are 50% chances that a girl may be born and 50% chances that a boy may beborn. It can be explained as follows:
Most human chromosomes have a maternal copy and a paternal copy. We have 22 such chromosomes. One pair of chromosomes called sex chromosomes is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes, both
called X. (XX)
But men have a mismatched pair of sex chromosomes in which one is normal sized – X chromosome while the other is a short one called Y chromosome. (XY)
A child receives one chromosome from mother which is essentially X chromosome.
A child who inherits an X chromosome from her father will be a girl, and one who inherits a Y chromosome from him will be a boy.
Question 29
The most obvious outcome of the reproductive process is the generation of individuals of similar design, but in sexual reproduction they may not be exactly alike. The resemblances as well as differences are marked. The
rules of heredity determine the process by which traits and characteristics are reliably inherited. Many experiments have been done to study the rules of inheritance.
(i) Why an offspring of human being is not a true copy of his parents in sexual reproduction ?
(ii) While performing experiments on inheritance in plants, what is the difference between F1 and F2 generation ?
(iii) (A) Why do we say that variations are useful for the survival of species over time ?
(iii) (B) Study Mendel’s cross between two plants with a pair of contrasting characters.
RRYY × rryy
Round Yellow Wrinkled Green
He observed 4 types of combinations in F2 generation. Which of these were new combinations ? Why do new features which are not present in the parents, appear in F2 generation
Summary
This CBSE Important Questions for Heredity and Evolution with answers is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.
