Answer:
A = Activator
B = Effector
Explanation:
An activator is a protein which typically binds to a short (50–1500 bp) region of DNA which might be located either upstream (mainly) or downstream of a gene so as to cause increased transcription. This particular region of DNA is known as enhancer and activator is also known as transcription factor. Activator is a trans-acting factor which binds to the cis-acting factor which is enhancer so as to enhance transcriptional expression.
But another protein named as effector may restrict activator from binding to the enhancer leading to a decrease in transcriptional expression by binding to the activator allosterically. Allosteric binding of effector to the activator causes conformational change in activator so it can no longer bind the enhancer.
I think its B it sounds more right than the others
Answer: A.it is a relatively new human adaptation.
Explanation:
Fight or flight response is a response shown by a human or animal body towards acute stress. It is a physiological reaction that occurs in response to the perceived attack, survival threat and attack. The animals or humans react to threats by the hormonal secretion from sympathetic nervous system. This prepared animals for fighting. The hormonal secretions like catecholamines, epinephrine and nonepinephrine helps in generation of response. Neurotransmitters dopamine, estrogen, testosteron e and cortisol affects how organisms react to the stress.
Fight-or-flight reaction is not a relatively new human adaptation but it is evolved as a survival mechanism which was also present in primitive human beings and mammals and helped them to react in the life-threatening situations.
