Answer:
Option B
Explanation:
The formal study of fossils, its collection and documentation started in 1700s during the period known as “Age of Enlightenment” It was during this time period that scientist noticed rock fossils and started making fossil collection. During the 1800s, areas with rocks fossils were studied and compared.
Further, Charles Lyell and Charles Darwin showed strong connection between biological evolution and geological evolution of planet earth. Hence, the earlier traces of fossils i.e before a certain period could not be studies due to late pioneering of fossil based evolutionary science. It is also due to limitations with radioactive dating
Hence, option B is correct
Answer:
The intracellular molecule produced by the receptor ligand complex is called Second messenger.
Explanation:
Receptors are membrane bound proteins which bind to the ligands which are also called first messengers and cause cellular changes. These intracellular changes are mediated by second messengers such as proliferation, differentiation, migration, apoptosis, transcription, contractions etc. They are specific for specific first messengers such as homones and growth factors. They relay the signals between the ligands to their target molecules in the cytosol or nucleus. Most common second messengers are cAMP, cGMP, DAG, IP3.
Signal amplification by second messenger can be explained by the example of IP3 which cayses the release of Calcium ions from the intracellular stores and cause contractions.
Answer: If the F2 occurs in the ratio 9 blue:3 pink:4 white, one gene pair (i.e 2 genes) control the flower color phenotype.
Explanation: This principle is called INCOMPLETE DOMINANCE where one gene (dominant) won't completely override the other (recessive).
Let assume B represents the dominant gene and b represents the reccesive gene. Let also assume that Blue color is dominant over white color. We can assign the genotype as follows;
Homozygous dominant genes BB will produce Blue color
Homozygous recessive genes bb will produce white color
Heterozygous genes Bb will produce pink color.
Therefore, a pair of gene ( 2 genes) will determine the flower color phenotype.
The answer is A
Mucus protects the stomach lining from digestive secretions
