Oxygen in the atmosphere nearly 21 % other wise there was no oxygen in the atmosphere
when the first prokaryotic species occurred in the earths history some .5 to 2 billion years ago oxygen started building up in the atmosphere as O2 was released as by product in photosynthesis reaction
Answer:
D
Explanation:
Sunlight is radiant energy, a type of kinetic energy that travels in waves.
Answer:
Ecology is the branch of biology concerning the spatial and temporal patterns of the distribution and abundance of organisms,including the causes and consequences
Answer:The above statement is "false".
Explanation:
The following events take place during contraction-relaxation of a muscle:
•Action potential in T tubule activates voltage-sensitive receptors,which in turn trigger Ca ions release from terminal cisternae of sacroplasmic reticulum(SR) into cystol.
•Ca ions bind to troponin;troponin changes shape,removing the blocking action of tropomyosin;actin active sites is exposed.
•CONTRACTION; myosin heads alternatively attach to actin and detach,pulling the actin filaments toward the center of the sarcomere;using ATP in this process.
•removal of Ca ions by active transport into the SR after the action potential ends.
•RELAXATION occurs.Actin and myosin return back to its unbound state.
