JSIERT

The fact that a person acquires certain experiences and attributes throughout his or her lifetime prevents such experiences and traits from being passed on to future generations. These are not characteristics that man is born with, and he cannot pass them on to his offspring. The following examples could clarify these better: (j) A child …

With the help of two suitable examples, explain why certain experiences and traits earned by people during their lifetime are not passed on to their next generations. When can such traits be passed on? (AI 2017) Read More »

The branch of biology called genetics is involved with the study of heredity and variation. William Bateson first used the word “genetics” in 1906. Small populations have fewer and narrower variances, which results in less variety and less variation in traits. From a genetic view, the fact that there are so few surviving tigers is concerning …

define genetics. Why is decrease in the number of surviving tigers a cause of concern from the point of view of genetics? Explain briefly. (AI 2019) Read More »

Acquired trait:A personality trait that an individual develops as a result of external effects is known as an acquired trait.Inherited trait:Traits that are inherited are those that transfer from parents to offspring. Genes control the inherited characteristics of an individual. Differences between the inherited traits and acquired traits are as follows : Inherited traits Acquired …

List two differences between acquired traits and inherited traits by giving an example of each. (Delhi 2019) Read More »

A group of mice will normally breed, and every offspring will have a tail. Therefore, tail-less mice won’t be generated if the tails of these mice are surgically removed after each generation. This is the case due to the acquired nature of mice’s tail removal, which is not passed down to the next generations. The mice’s …

Why do mice whose tails were surgically removed just after birth for generations, continue to produce mice with tails? (Foreign 2014) Read More »

Charles Darwin decided to make a major contribution to the field of evolution by stating that only organisms that can adapt to changing environmental conditions can survive. He also asserted that natural selection is a process that plays a significant role in the evolution of plants and animals by selecting organisms that have traits that …

Write the contribution of Charles Darwin in the field of evolution. (Delhi 2014) Read More »

(a) Heredity is the mechanism by which variations are created and inherited. (b) Evolution is the process in which the development of a new type of organism takes place from the existing ones.

Garden peas were Mendel’s initial selection for his experiment because: (I) It was simple to grow and shows some distinct contrastive traits, such as some pea plants being tall and others being dwarf.(ii) Pea plants are self-pollinating, which allows for the production of numerous generations in a very short amount of time. (a) Mendel observed the …

(a) Why did Mendel choose garden pea for his experiments ? Write two reasons.
(b) List two contrasting visible characters of garden pea Mendel used for his experiment.
(c) Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive. (Foreign 2016) Read More »

(a) Mendel found that only tall pea plants were produced in the first generation when he crossed pure-bred tall pea plants with pure-bred dwarf pea plants (F1). The tall plants and dwarf plants were produced in the second generation, or (F2), in a ratio of 3:1. He then self-crossed the tall pea plants of the …

How do Mendels experiments show that
(a) traits may be dominant or recessive?
(b) inheritance of two traits is independent of each other? (Delhi 2017) Read More »

Human beings have 23 pairs(46) of chromosomes (22 pairs of autosomes +1 pair(2) of sex chromosomes). A male has one X chromosome and one Y chromosome whereas a female has XX chromosomes. The sex of a child depends on the two conditions which take place during fertilisation. The two conditions are given below: If a …

How is the sex of the child fixed during the fertilisation, step in human beings? Explain. (Foreign 2011) Read More »

(A) The F1 generation of plants will all be tall plants.(b) The F2 generation has a 3:1 ratio of tall to dwarf plants.(c) Dwarf plants first arose in the F2 general ion and were not present in the F1 generation. This is because only the dominant trait (tall) expresses itself in the F1 generation, while …

If we cross pure-breed tall (dominant) pea plants with pure-breed dwarf (recessive) pea plants we will get pea plants of the F1 generation.
If we now self-cross the pea plant of the F1 generation, then we obtain pea plants of the F2 generation.
(a) What do the plants of the F1 generation look like?
(b) State the ratio of tall plants to dwarf plants in the F2 generation.
(c) State the type of plants not found in the F1 generation but appeared in the F2 generation, mentioning the reason for the same. (AI 2012) Read More »