Answer:
hgxfgjhfhfkfjhhfgdhjfhgdghkjfjgjfghck.jhfxb
Explanation:
Persistent chlorinated hydrocarbon pesticides persist in the environment and accumulate in the foods chain causing harmful effects on the environment including posing a threat to humans health in the long term. Nonpersistent organophosphate pesticides are more toxic than the former but degrade after a short life span. Therefore they cause immediate harm in case one is in contact with them.
The fact that they do not accumulate in the environment, they are more favourable than chlorinated hydrocarbon pesticides. Chlorinated hydrocarbon pesticides will affect several generations due to their accumulation in the environment. However they don't need to be re-applied hence are less expensive
Answer:
For about 4.5 million years, and still exist on earth
Explanation:
Humans are the most highly complex organisms and are comprised of well-developed brains. It shows advanced characteristics and is well developed social animals that can adapt well in any environment.
The humans are one of the major God's creation which has played and still playing a great role on earth.
These human beings were first appeared on earth about 4.5 million years back, during the time of Pliocene. These were the Hominoids and Australopithecus, from which they have evolved and became more advanced. They represent on earth since the Pliocene and still exist on earth.
Thus, it can be estimated that they are found to be present for about 4.5 million in the geological time scale and is the major and dominant species on earth now.
Answer: 1,2,3
Explanation:
1. One of the major function of the kidney is to excrete metabolic waste. When the blood is perfused through the Bowman's capsule, an ultrafiltrate of the blood is produced in the glomerulus, the filtrate in Bowman's capsule contains salt, glucose, amino acids, nitrogenous waste, etc while the cells and proteins are retained in the blood. The waste are excreted as urine or uric acid.
2. One of the function of the renal tubule is to maintain fluid and electrolytes balance. When the glomerulus filtrate is formed, it contains almost all the crystalloids of plasma which includes water, Na+, Cl-, glucose, amino acid and K+. The renal tubule reabsorb water and solute to the blood to maintain water and electrolytes balance.
3. The kidney secrete a hormone Renin, which control other hormones angiotensin and aldosterone that helps to control blood pressure.
Answer:
At the neuromuscular junction, calcium must enter the synaptic end bulb to stimulate the release of acetylcholine, which binds to ligand gates so sodium ions can enter the muscle fiber.
Explanation:
Skeletal fiber contractions are based on different physiological and biochemical phenomena that happen in every cell. These phenomena are due to stimulation produced by somatic motor neurons, which axons get in contact with muscle fibers through a neuromuscular synapse. In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When an action potential is originated in the central nervous system, it travels to the somatic motor neuron membrane: the muscle fiber, and <u>activates the calcium channels releasing it in the neuron</u>. <u>Calcium</u> makes vesicles to fuse with the membrane and <u>release the neurotransmitter named acetylcholine (Ach)</u> into the synaptic space in the juncture. Then, <u>Ach binds to its receptors on the skeletal muscle fiber</u>. This causes the <u>ion channels to open</u>, and positively charged <u>sodium ions cross the membrane</u><u> </u><u>to get into the muscle fiber</u> (sarcoplasm) and potassium get out. The difference in charges caused by the migration of sodium and potassium makes the muscle fiber membrane to become more positively charged (depolarized). The action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane, that make the calcium be released into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin binds to the uncovered actin-binding sites, and while doing it ATP is transformed into ADP and inorganic phosphate. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.