The concept of 'survival of the fittest' was proposed by:
A. De Vries
B. Mendel
C. Darwin
D. Lamarck
Answer: Option C
Solution (By JKExamLibrary)
'Survival of the fittest' was a phrase used by Herbert Spencer but adopted by Darwin to describe natural selection—organisms best adapted to the environment survive and reproduce. Lamarck proposed inheritance of acquired characters, Mendel discovered laws of heredity, De Vries proposed mutation theory. Darwin's theory emphasizes differential reproductive success of variants.
Explanation:
A test cross is used to determine the genotype of an individual expressing a dominant phenotype by crossing it with a homozygous recessive individual. The resulting phenotypic ratios reveal whether the dominant individual is homozygous (all offspring dominant) or heterozygous (1:1 ratio). It is a valuable tool in genetic analysis.
Explanation:
Peyer's patches are organized lymphoid follicles (aggregated lymphoid nodules) located in the mucosa and submucosa of the small intestine, most abundantly in the ileum (the distal part). They are a crucial component of the gut-associated lymphoid tissue (GALT) and play a vital role in monitoring intestinal bacteria populations, preventing the growth of pathogenic bacteria, and training the immune system to recognize antigens.
Explanation:
The law of independent assortment states that alleles of different genes segregate independently of each other during gamete formation, provided the genes are on different non-homologous chromosomes. If genes are linked (on the same chromosome), they tend to be inherited together unless crossing over occurs. This law was derived from Mendel's dihybrid crosses, yielding the 9:3:3:1 ratio.
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