Answer:
Your heart changes its rate depending on the activity, so that it can carry blood to your muscles, and therefore it needs to beat stronger if you are performing some exercise, or not so strong if you are sleeping, for example.
Explanation:
Your heart is continuously beating to keep blood circulating throughout your body.
So, here it is why your heart changes its rate: Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level.
And how: depending on your activity level, your heart has to pump enough blood to your muscles. Blood carries needed oxygen and other nutrients. Muscles need more blood sugar than any other tissue especially when working hard. To supply your muscles with oxygen your heart needs to beat faster, and this builds up your heart muscles.
Answer:
Cellular respiration that proceeds in the absence of oxygen is anaerobic respiration. Cellular respiration that proceeds in the presence of oxygen is aerobic respiration. Anaerobic respiration evolved prior to aerobic respiration.
D. An element donates an electron to another element.
Answer: Life span, Life expectancy.
Explanation:
Answer: c) amino acid
Explanation: A codon is an mRNA sequence which contains three nucleotides that codes for a particular amino acid. The codons on the mRNA are read by the ribosome during translation and the amino acid coded for by each codon is used to make a protein. There are 64 different codons in existence, each amino acid is coded for by at least one codon. Some amino acids have more than one codon. For example, the amino acid Leucine is coded for by six codons: UUA, UUG, CUU, CUC, CUA and CUG while the amino acid phenylalanine is coded for by two codons: UUU and UUC.
