Answer:
A
Explanation:
Reptiles arose about 310–320 million years ago during the Carboniferous period.
The sequence of impulse through the cardiac conduction system starts from SA node passes to AV node to atrioventricular bundle fibers and finally to Purkinje fibers.
Heart is an organ that receives oxygenated blood form lungs and deoxygenated blood from different parts of body. Oxygenated blood is transported to different organs and deoxygenated blood is transported to lungs for oxygenation.
Now, to perform this transportation, the auricles and ventricles of heart contract and relax. In order to contract and relax, impulse generation is required, which begins at SA node or Sinoatrial node. It is also referred to as pacemaker of the heart. SA node contracts the atria and the impulse transfers to AV node or Atrioventricular node.
This is followed by transfer of impulse to atrioventricular bundle fibers which further passes it on to Purkinje fibres for ventricular contraction. Now the blood is sent to lungs and aorta as per it's oxygen status.
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Answer:
False
Explanation:
Approximately 200 out of 200 million sperms ejaculated during intercourse reach the general vicinity of the egg. They sperms must undergo capacitation during which dilute inhibitory factors fluids of the female reproductive tract weaken the membrane of the sperm head so that head of the sperm can be broken easily when it came in contact with the egg.
The first sperm to reach an egg isn’t the one to fertilize it because the egg is surrounded by a gelatinous membrane called the zona pellucida. Outside this layer, a layer of small granulosa cells also present.
Therefore, it requires numerous sperm to clear a path through these barriers before one of them can penetrate the egg and fertilize it.
Answer:
glucose and oxygen:C6H12O6 and 6O2 respectively
I've checked all the options and I think that the right answer looks like this: Mollusks have highly developed olfactory receptors.
