The production of gametes by the parents, the formation of zygotes, and the F1 and F2 plants, can be understood from a diagram called :
The production of gametes by the parents, the formation of zygotes, and the F1 and F2 plants, can be understood from a diagram called :
Net square
Bullet square
Punch square
Punnett square
The Correct Option is D
Solution and Explanation
The question is about understanding a diagram used in genetics to predict the genotypes of offspring from a particular cross or breeding experiment.
The correct answer to the question is the Punnett square.
The Punnett square is a square diagram that is used in genetics to predict the genotypes of a particular cross or breeding experiment. This tool allows us to visualize the way alleles of genes segregate and combine during sexual reproduction.
- Step 1: Understanding How Gametes Combine - During sexual reproduction, each parent contributes one allele for a trait, randomly, from their pair of alleles. The Punnett square helps visualize this combination process by showing all possible combinations of parental alleles.
- Step 2: Formation of Zygotes - The combinations shown in the Punnett square are the potential genotypes of the offspring or zygotes resulting from this cross.
- Step 3: Analyze the Resulting Generations - By examining the Punnett square, one can predict the genotypes and phenotypes of the F1 (first filial) and F2 (second filial) generations.
Here is an example diagram of a Punnett square for a monohybrid cross between two heterozygous parents:
In this diagram, each box represents a possible genotype for the offspring. For example, if looking at a trait governed by two alleles 'A' (dominant) and 'a' (recessive), a Punnett square of a cross between Aa x Aa yields offspring with genotypes in the ratio 1:2:1 (1 AA, 2 Aa, 1 aa), which also explains the phenotypic ratio for the trait if 'A' is dominant over 'a'.
This explanation makes it clear why the correct answer is the Punnett square and helps you understand how to interpret genetic information through this diagrammatic approach.
Top Questions on Evolution
- (a) “The process of evolution of different species in a given geographical area starts from a point and literally radiates to other geographical areas.” Explain it with an example.
(b) Cite an example where more than one adaptive radiation has occurred in an isolated geographical area. Name the type of evolution your example depicts. - (a) "The process of evolution of different species in a given geographical area starts from a point and literally radiates to other geographical areas." Explain it with an example.
(b) Cite an example where more than one adaptive radiation has occurred in an isolated geographical area. Name the type of evolution your example depicts. - A few stages and their respective time period in the evolutionary history of human beings are mentioned in the flowchart given below:
- 15 mya — Primates walking like gorillas and chimpanzees existed.
- 3–4 mya — Man-like primates walked in Eastern Africa. Fossils of their bones were discovered.
- 2 mya — This ancestor lived in the East African grasslands and ate fruits.
- 1.5 mya — This hominid had a brain size of 900 cc and probably ate meat.
- [(a)] Name one primate about 15 mya.
- [(b)] Name one place where fossils of primates were discovered in Eastern Africa.
- [(c)] Name the ancestor that lived in the East African grasslands about 2 mya.
- [(d)] Name the hominid that was found around 1.5 mya.
The given graph shows the range of variation among population members, for a trait determined by multiple genes. If this population is subjected to disruptive selection for several generations, which of the following distributions is most likely to result?
Read the following passage and answer the questions that follow. According to evolutionary theory, every evolutionary change involves the substitution of a new gene for the old one and the new allele arises from the old one. Continuous accumulation of changes in the DNA coding for proteins leads to evolutionary differences. The chemical composition of DNA is basically the same in all living beings, except for differences in the sequence of nitrogenous bases. Given below are percentage relative similarities between human DNA and DNA of other vertebrates:
(a) What is the term used for the substitution of a new gene for the old one and the new allele arising from the old one during evolutionary process?
(b) Which one of the following holds true for the data provided in the above table?
- [(A)] Greater the evolutionary distance, greater are the differences in the nitrogenous bases.
- [(B)] Lesser the evolutionary distance, greater are the differences in the nitrogenous bases.
- [(C)] Greater the evolutionary distance, lesser are the differences in the nitrogenous bases.
- [(D)] Lesser the evolutionary distance, lesser are the differences in the nitrogenous bases.
(c) [(i)] To which category of evolution (divergent or convergent) does the following relationship belong? Justify your answer.
Human and Rhesus Monkey
OR[(ii)] Differentiate between Convergent and Divergent evolution.
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Concepts Used:
Non-Mendelian Genetics
The term - non-mendelian inheritance refers to any pattern of heredity in which features do not separate according to Mendel's laws. These principles describe how features linked with single genes on chromosomes in the nucleus are passed down through generations.
Types of Non-Mendelian Inheritance
Codominance Inheritance
It is a form of incomplete dominance in which both alleles for the same feature are expressed in the heterozygote at the same time. For example, the MN blood types of humans.
Incomplete Dominance
In a heterozygote, the dominant allele does not always completely cover the phenotypic expression of the recessive gene, resulting in an intermediate phenotype which is referred to as "incomplete dominance”.