Answer:
The nervous system and circulatory system
Explanation:
1. The appearances of fireflies at dusk is an example of a circadian rhythm because it's happens daily. The correct option among all the options that are given in the question is the third option or option "c".
2. During migration, animals undertake a seasonal movement. The correct option among all the options that are given in the question is the first option or option "a".
Answer:
All biological enzymes function best at particular pH values (most require pH 6 to 7) in the human stomach, the pH of 2-3 provides the environment required for the proper functioning of the digestive enzymes found there and this is the perfect condition for preservation of food and digestion of food.
Explanation:
The adding of basic material decrease acidity that happens due to the lower pH of the stomach. The very common basic material which is used to neutralize the acidity of stomach milk of magnesia.
The lower pH of the stomach cause acidity which is injurious to the health and also the mucous lining of the stomach. To balance is acidity milk of magnesia is required.
Answer:
Until recent history,extinctions have always happened gradually and on a small scale.
Explanation:
Extinction occur when environmental factors like natural disaster,habitat fragmentation,over exploitation,global change don't favor the survival of species thus gradually leads to extinction of species.
Some times human activity becomes the major problem for extinction.More over,poor reproduction,decline in population number and genetic inbreeding also leads to extinction.
99% of all species that exist on earth become disappeared.
Evolution leas to speciation which leas to formation of new species but species become extinct when they are unable to survive against competition.
