Chapter: Life Sciences
One advantage of sexual reproduction over asexual reproduction is that it helps species to survive over long evolutionary time. This is because sexual reproduction produces :
Sexual reproduction results from the combination of genetic material from two parents, enhancing genetic diversity.
This process begins with meiosis, where gametes (sperm and egg) are formed, leading to fertilization that creates a zygote with unique genetic combinations.
Remember "Sowing Diversity Grows Survival" (SDGS) to recall that sexual reproduction's strength lies in creating diverse offspring for better adaptation.
Illustrate a flowchart showing the process of meiosis leading to genetic variation in offspring during sexual reproduction. Include inputs from two parent organisms and the resulting unique offspring.
Verified against NCERT Class XII Biology, Chapter 13 (Organisms and Populations).
Which is the correct pairing found in a normal DNA molecule?
Option A is correct. Adenine pairs with thymine.
DNA is a double helix molecule composed of four nitrogenous bases that pair specifically: adenine with thymine and cytosine with guanine, ensuring stability and fidelity during replication.
Remember the pairing rules: "A-T, C-G" for quick recall of DNA base pairings.
Adenine pairs with thymine (A-T), and cytosine pairs with guanine (C-G) in DNA structure.
Different varieties of the same gene are called
Alleles are different forms of a gene that arise by mutation and are found at the same place on a chromosome.
The genetic constitution of an organism (its genotype) can vary due to the presence of different alleles. This leads to phenotypic variations, influencing traits such as eye color or blood type, which can be distinctly observable.
A: Genotypes - Representation of an organism's genetic makeup, not varieties of the same gene.
B: Sib pairs - Refers to siblings in genetic studies to analyze inheritance patterns.
D: Isomers - Chemical compounds with the same formula but different structural arrangements, unrelated to genetics.
Remember: "Alleles are A-like." Both start with 'A' and refer to variations of a gene.
A diagram illustrating a chromosome with different alleles at a specific gene locus (e.g., A1, A2). Each allele can be exemplified with different colors to indicate variations, showcasing how they affect the expression of traits.
Verified against NCERT Class 11 Biology, Chapter 5 (Principles of Inheritance and Variation).
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