A. cacti
A biotic factor is a living factor.
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Answer:
Not necessarily.
Explanation:
An erection is caused by blood flow to the penis. A man can get an erection just by seeing a woman or hearing language that turns him on or excites him. A young man who is not experienced in controlling an erection may release sperm in a spontaneous ejaculation but more experienced men would not likely ejaculate without more stimulation, such as masturbation.
Answer:
To study these moths, Dr. Kettlewell placed light and dark moths on the trunks of trees where he could observe them. The same birds would find the dark moth twice as often if the bark on the tree was light. This supported the idea that dark moths had a survival advantage in a dark forest.