CBSE Class 10 Biology Heredity And Evolution Worksheet Set A

Read and download free pdf of CBSE Class 10 Biology Heredity And Evolution Worksheet Set A. Students and teachers of Class 10 Biology can get free printable Worksheets for Class 10 Biology in PDF format prepared as per the latest syllabus and examination pattern in your schools. Standard 10 students should practice questions and answers given here for Biology in Grade 10 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 10 Biology Worksheets prepared by school teachers as per the latest NCERT, CBSE, KVS books and syllabus issued this academic year and solve important problems provided here with solutions on daily basis to get more score in school exams and tests

Heredity And Evolution Class 10 Biology Worksheet Pdf

Class 10 Biology students should refer to the following printable worksheet in Pdf for Heredity And Evolution in standard 10. This test paper with questions and answers for Grade 10 Biology will be very useful for exams and help you to score good marks

Class 10 Biology Worksheet for Heredity And Evolution

Heredity and Evolution

Question : Explain the importance of fossils in deciding evolutionary relationships.

Answer: Fossils are the remains of the organism that once existed on earth. They represent the ancestors of the plants and animals that are alive today. They provide evidences of evolution by revealing the characteristics of the past organisms and the changes that have occurred in these organisms to give rise to the present organisms. Let us explain the importance of fossils in deciding evolutionary history with the help of the following example.

Around 100 million years ago, some invertebrates died and were buried in the soil in that area. More sediment accumulated on top of it turning it into sedimentary rock.
At the same place, millions of years later, some dinosaurs died and their bodies were buried on top of the sedimentary rock. The mud containing dinosaurs also turned into a rock.
Then, millions of years later, some horse-like creatures died in that area and got fossilized in rocks above the dinosaur fossils.Some time later, due to soil erosion or floods in that area, the rocks containing horselike fossils are exposed.
If that area is excavated deeper, then the dinosaur and invertebrates fossils can also be found. Thus, by digging that area, scientists can easily predict that horse-like animals evolved later than the dinosaurs and the invertebrates.
Thus, the above example suggests that the fossils found closer to the surface of the earth are more recent ones than the fossils present in deeper layers.


Question : An example of homologous organs is
(a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.

Answer: (b)An example of homologous organs is our teeth and an elephant’s tusks.


Question : Why are traits acquired during the life-time of an individual not inherited?

Answer: This happens because an acquired trait involves change in non-reproductive tissues (somatic cells) which cannot be passed on to germ cells or the progeny. Therefore, these traits cannot be inherited.


Question : In evolutionary terms, we have more in common with

(a) a Chinese school-boy.

(b) a chimpanzee.

(c) a spider.

(d) a bacterium.

Answer: (a) In evolutionary terms, we have more in common with a Chinese school boy.


Question : Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

Answer: Small numbers of tigers means that fewer variations in terms of genes are available.This means that when these tigers reproduce, there are less chances of producing progeny with some useful variations. Hence, it is a cause of worry from the point of view of genetics.


Question : Why do all the gametes formed in human females have an X chromosome? 

Answer:  Women have a perfect pair of sex chromosomes, both called X. Women are XX, while men are XY. All children will inherit an X chromosome from their mother regardless of whether they are boys or girls. Thus, the sex of the children will be determined by what they inherit from their father. A child who inherits an X chromosome from her father will be a girl. During meiosis, one X chromosome enters each gamete. Hence, all the gametes formed in human females have an X chromosome.


Question :Do all variations in a species have equal chances of surviving in the environment in which they find themselves?

Answer: No, all variations in a species do not have equal chances of surviving in the environment in which they find themselves. Depending upon the nature of variations, each individual would have different advantages of survival.


Question : How is the normal number of chromosomes restored in the progeny of sexually reproducing organisms?

Answer: Each cell has two copies of each chromosome, one each from the male and female parents. Each germ cell or gamete takes one chromosome from each pair and when two germ cells combine, the original number of chromosomes is restored in the progeny.


Question : Give reasons for the appearance of a new combination of characters in the F2 progeny.

Answer: F1 plants have round and yellow seeds. In F1 generation, the dominant alleles suppress the recessive ones. So, as a result, only dominant alleles are expressed. Thus, all the progenies in the F1 generation; showed dominant traits only. However, genes for recessive traits were present in all the plants. When the F1 generation is crossed, it gives rise to new combinations in the F2 generation with round-yellow, round- green, wrinkled yellow and wrinkled-green in the ratio of 9: 3: 3: 1.  This indicates that the chances for the pea seed  to be round or wrinkled do not depend on their chances to be yellow or green. Each pair of alleles is independent of the other pair. This is known as ‘principle of independent assortment’.

 

More Question

1. Name some tools for tracing evolutionary relationships.

2. “ It is not as if one species is eliminated to give rise to a new one “ justify the statement.

3. What do we understand by the term ‘ artificial selection ‘

4. Match the following:

Sterile flowers Kohlrabi

Arrested flower development Cauliflower

Swollen parts Broccoli

Larger leaves Kale

5. During evolution,a change that is useful for one property to start with can become useful later

for quite a different function. Explain with the help of an example.

6. How can we find out age of fossils.

7. What is the relationship of classification & evolution?

8. Explain genetic drift.

9. Why do we find very little variations among sugarcane plants.

10. Why did Mendel choose pea plant for his experiments.

11. What is the difference between dominant & recessive gene.

12. With the help of an example show that genes control traits.

13. Give some contrasting characters seen in pea plant.

14. Name an animal which can change its sex.

15. Name the homologous organs of three animals.

16. What name is given to the sequence of gradual changes over millions of years in which new species are formed.

17. With the help of a diagram show how sex is determined in human beings.

18. A mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bear violet flowers but almost half of them were shown. Suggest the genetic make up of the tall parent.

19. What would be the genotypic ratio in F2 generation of monohybrid cross.

20. If a plant is heterozygous for tallness,the F2 generation has both tall and dwarf plants. Which principle does it prove?

 

Please click the below link to access CBSE Class 10 Biology Heredity And Evolution Worksheet Set A

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