Answer:
air resistance or drag, (Option B)
Explanation:
Animal cells complete the cell cycle because the nucleus in the cell and They replicate which make more cells
Answer: The calcium ion binds to troponin, and this slides the tropomyosin rods away from the binding sites.
Explanation:
Contraction and relaxation of muscle cells brings about movements of the body. The contractile myofilament called sarcomeres are bounded at each end by a dense stripe called the Z - line, to which the myosin fibres are attached, and lying in the middle of the sarcomere are the actin filaments, overlapping with the myosin.
When action potential spreads from the nerve along the sarcolemma (muscle cell membrane), it penetrates deep into the muscle cell through the sarcoplasm (cytoplasm of muscle cell), and releases CALCIUM from the intracellular stores.CALCIUM triggers the binding of myosin to the actin filament next to it forming CROSS BRIDGES.
For this to occur, ACTIN BINDING SITE has to be made available. TROPOMYOSIN is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. The first step in the process of contraction is for calcium ions to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands.
<span>In the past, human populations were controlled by </span>Disease and Famine
Answer:
4 reasons here:
Explanation:
1) Adventure; boredom causes them to look for excitement, even if it's detrimental to their health.
2) Peer pressure;research shows that risk-taking among teens doubles when peers are around.
3) media;easy to guess, shows a lot of risky behaviour in glamorous or admirable ways.
4) Poor self-esteem; bullying can lead to poor self-esteem and higher chance of the victim becoming depressed and taking substance to cope with the depression, also leads to err, self-death
