Answer:
The covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bond.
Answer:
Minivalves
Explanation:
Lymphatic capillaries are so much permeable that some researchers thought that they are open from one side but scientists found that this permeability is due to some structural modification.
The endothelial cell that forms the lymphatic capillaries wall are not packed tightly and overlap each other very loosely which makes easy openings in the structure called mini valves.
When the pressure of fluid in interstitial space is high then the mini valves become open and allow the fluid to enter the lymphatic capillary. So mini valves are the unique structural modification that increases permeability in lymphatic capillaries.
Yes, when the egg and a sperm cell meet fertilization has taken place
Answer:
faced a struggle for survival
Explanation:
The woolly mammoths became extinct, unlike the other species, because the woolly mammoths faced a struggle for survival due to changing of environmental conditions. Global warming is the main cause of extinction of woolly mammoth which destroy their habitats about 10,500 years ago. The environmental conditions are not favourable for them so they faced struggle for survival which causes extinction of woolly mammoth.
Answer:
The phenotype is the result of the interaction between the genes (i.e., genotype) and environmental factors.
Explanation:
Cancer is a disease caused by abnormal expression of genes involved in the cell cycle, mitosis, DNA replication, etc. Moreover, the abnormal gene expression may be associated with environmental factors such as smoking, alcohol consumption, etc.
