E X E R C I S E S CHAPTER 8 Heredity SCIENCE NCERT TEXTBOOK (CBSE) CLASS 10:

E X E R C I S E S  

CHAPTER  8 Heredity 


1. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as:

Answer: (d) TtWw

  • Explanation: The tall parent must have a heterozygous genotype for height (Tt), as the progeny had both tall and short plants. The violet flower colour is likely dominant (W), and since the flowers were all violet, the tall parent must have had one dominant (W) allele. The short plants in the progeny suggest that the short parent contributed a recessive (w) allele for flower colour and the tall parent could have a heterozygous genotype for this trait. Thus, the tall parent is most likely TtWw.

2. A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Answer: We can infer that the light eye colour trait is likely recessive.

  • Reasoning: If both parents have light-coloured eyes and the children predominantly have light-coloured eyes as well, this suggests that both parents likely carry two recessive alleles for the trait. For a recessive trait to be expressed, the individual must inherit one recessive allele from each parent. Therefore, the light eye colour is most likely a recessive trait.

3. Outline a project which aims to find the dominant coat colour in dogs.

Project Outline:

  • Objective: To determine the dominant coat colour in dogs.

Method:

  1. Selection of Parents: Choose two dogs with different coat colours (e.g., black and brown). Ensure that the parent dogs are purebred for their coat colour.
  2. Crossbreeding: Mate the two dogs and observe the coat colours of the offspring.
  3. Observation of Offspring: Record the coat colour of all the puppies in each generation.
  4. Analysis of Results: Based on Mendelian inheritance patterns, analyze whether the coat colour follows a dominant-recessive pattern. If one colour appears more frequently in the offspring, that colour is likely dominant.
  5. Genetic Testing: Optionally, perform genetic analysis of the parents and offspring to confirm the alleles responsible for coat colour.

Expected Outcome: The dominant coat colour will appear more frequently in the offspring, and this will help identify the dominant allele.

4. How is the equal genetic contribution of male and female parents ensured in the progeny?

Answer:

  • The equal genetic contribution of male and female parents is ensured through the process of sexual reproduction, where each parent contributes one allele for each gene.
  • In humans and most organisms, the male contributes one of two possible sex chromosomes (X or Y), and the female contributes one X chromosome. The offspring receive half of their genetic material from each parent, ensuring equal genetic contribution.
  • The process involves the fusion of male and female gametes (sperm and egg), each containing half of the parent's genetic material (haploid), resulting in a fertilized egg (zygote) with a complete set of chromosomes (diploid). This process guarantees that both the mother and father contribute equally to the genetic makeup of the offspring.

Comments

Post a Comment

Popular posts from this blog

NOTES Chapter 15: Our Environment Class 10 Science – CBSE NCERT

  Chapter 15: Our Environment Class 10 Science – CBSE NCERT Chapter 15 focuses on the various components that make up our environment, including ecosystems , biotic and abiotic factors , and food chains and webs . It highlights the balance of nature , biodiversity , and environmental issues like pollution, deforestation, and the need for sustainable development. The chapter also explains the impact of human activities on the environment and emphasizes the importance of conserving natural resources for future generations. 1. The Environment and Its Components The environment is the surrounding in which organisms live. It includes both living and non-living things and can be broadly classified into two categories: 1.1 Biotic Components : These are the living organisms in the environment. They include: Plants (producers), Animals (consumers), Microorganisms (decomposers). 1.2 Abiotic Components : These are the non-living factors that affect the living organisms in th...
Read more

NOTES Chapter 12: "Sound" from Class 9 Science CBSE NCERT:

  summary of Chapter 12: "Sound" from Class 9 Science CBSE NCERT : 1. What is Sound? Sound is a form of energy that is produced by the vibration of objects and propagates through a medium (solid, liquid, or gas) in the form of waves. Sound travels in waves and can be heard when it reaches our ears . How is sound produced? Sound is produced when an object vibrates. These vibrations cause the particles of the medium to move, creating compressions and rarefactions (regions of high and low pressure) that travel through the medium. 2. Propagation of Sound Sound needs a medium (like air, water, or solid objects) to travel. It cannot travel in a vacuum. How sound waves travel : Sound waves are longitudinal waves (particles of the medium move in the same direction as the wave). When an object vibrates, it creates a series of compressions (regions where particles are close together) and rarefactions (regions where particles are spread apart) in the surrounding medium. These co...
Read more

Moments Chapter 3 of CBSE Class 9, titled "Iswaran the Storyteller" by R.K. Narayan:

  summary of Chapter 3 of Moments for CBSE Class 9, titled "Iswaran the Storyteller" by R.K. Narayan : Summary: In this chapter, the story is centered around Iswaran , a cook who works for the narrator, and his fascinating way of telling stories. Iswaran's storytelling skills and his adventurous nature provide both entertainment and a sense of mystery to the narrator, who works in a small town. The narrator begins by describing Iswaran as an enthusiastic and talented cook who makes delicious food and is always happy to serve. Iswaran is very devoted to his job and never seems to get tired, no matter how much work is piled up. He is also well known for his remarkable storytelling abilities. He often entertains the narrator with thrilling stories, which he describes in vivid detail. The Background of Iswaran’s Life: Iswaran is originally from a village, and he later moves to the town where he works for the narrator. He is described as a "man of strong character...
Read more