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Lakhmir Singh & Manjit Kaur: Heredity and Evolution, Solutions- 1 | Science Class 10 PDF Download

Page No - 191

Question 1:
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Solution :
Sexual Reproduction 

Question 2:
Name one variation in humans connected with ears.
Solution :
Free Earlobes.

Question 3:
What constitutes the link between one generation and the next ?
Solution :
Gametes.

Question 4:
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 ?
Solution :
B.

Question 5:
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors ?
Solution :
Genes.

Question 6:
Some plants occur in one of the two sizes : tall or dwarf. This characteristic is controlled by one pair of genes. Tallness is dominant to dwarfness. Choose suitable letters for this gene pair.
Solution :
Tt.

Question 7:
What are the chromosomes XY and XX known as ?
Solution :
Sex Chromosomes.

Question 8:
Which of the two, sperm or ovum, decides the sex of the child ?
Solution :
Sperm.

Question 9:
State whether the following statement is true or false :
The sex of an infant is not a case of inheritance of characteristics.
Solution :
False.

Question 10:
A new born child has an XY pair of chromosmes. Will it be a baby boy or a baby girl ?
Solution :
Baby boy

Question 11:
Which of the following combinations of sex chromosomes produce a male child : XX or XY ?
Solution :
XY.

Question 12:
Name the first scientist who studied the inheritance of traits from one generation to the next.
Solution :
Gregor Mendel

Question 13:
What type of plants were used by Mendel for conducting his experiments on inheritance ?
Solution :
Pea plants.

Question 14:
The gene for red hair is recessive to the gene for black hair. What will be the hair colour of a person if he inherits a gene for red hair from his mother and a gene for black hair from his father ?
Solution :
Black hair.

Question 15:
What are the four blood groups in humans ?
Solution :
A, B, AB and O.

Question 16:
Name one reptile in each case where higher incubation temperature leads to the development of : (a) male progeny, (b) female progeny.
Solution :
(a) Lizard (Agama agama)
(b) Turtle (Chrysema Picta)

Question 17:
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.
Solution :
(a) Pairs.
(b) Recessive; Dominant.
(c) Free; attached.
(d) 23; 46.
(e) Four.
(f) Sex; Female; male.

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FAQs on Lakhmir Singh & Manjit Kaur: Heredity and Evolution, Solutions- 1 - Science Class 10

1. What is heredity and evolution?
Ans. Heredity refers to the passing on of traits or characteristics from parents to offspring through genes. Evolution, on the other hand, is the process through which species of organisms change over successive generations. It is driven by the mechanism of natural selection, which allows individuals with favorable traits to survive and reproduce, leading to the accumulation of beneficial traits in a population over time.
2. How are genes involved in heredity?
Ans. Genes are segments of DNA that contain instructions for the development and functioning of an organism. They are responsible for the transmission of traits from parents to offspring. Each gene carries specific information that determines a particular characteristic or trait. During reproduction, genes from both parents combine and are passed on to the offspring, resulting in the inheritance of traits.
3. What are the factors that contribute to evolution?
Ans. Evolution is influenced by several factors, including natural selection, mutation, migration, genetic drift, and reproductive isolation. Natural selection acts upon variations within a population, favoring individuals with traits that enhance their survival and reproductive success. Mutations introduce new genetic variations, which can be selected for or against. Migration allows the movement of genes between populations, while genetic drift refers to random changes in gene frequencies. Reproductive isolation leads to the formation of new species by preventing gene flow between populations.
4. Can heredity be influenced by environmental factors?
Ans. While heredity is primarily determined by genetic factors, environmental factors can also play a role in the expression of certain traits. Environmental factors such as nutrition, exposure to toxins, and stress can interact with genetic factors to influence the development and expression of traits. For example, a person's height may be determined by their genetic makeup, but it can also be influenced by factors such as nutrition during childhood.
5. How does evolution explain the diversity of life on Earth?
Ans. Evolution explains the diversity of life on Earth through the process of speciation. Over millions of years, species have evolved and diversified through natural selection and other evolutionary mechanisms. This has led to the emergence of new species with unique characteristics and adaptations to different environments. The accumulation of small genetic changes over time, combined with the branching of populations and the formation of reproductive barriers, has resulted in the vast array of organisms we see today.
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