How male urinary system can carry semen and urine through a single tube?

The Urethra

Explanation:

It is called the urethra. It is hollow and carries urine from the bladder through the penis to the outside. ... In this case, the urethra acts as a tube for semen to be ejaculated into the vagina. When you ejaculate, seminal fluid and seminal vesicles mix with sperm to form semen.

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many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.