Biology: The Unity and Diversity o...

15th Edition
Cecie Starr + 3 others
ISBN: 9781337408332



Biology: The Unity and Diversity o...

15th Edition
Cecie Starr + 3 others
ISBN: 9781337408332
Textbook Problem

A male attains an erection when ___ .

  1. a. muscles running the length of the penis contract
  2. b. Leydig cells release a surge of testosterone
  3. c. the posterior pituitary releases oxytocin
  4. d. spongy tissue inside the penis fins with blood.

Summary Introduction

Concept introduction: The male reproductive system helps to produce sperm by spermatogenesis that is bathed in liquid called semen. The sperm and the semen are released through the penis into the female reproductive tract during sexual intercourse.


Reason for correct statement:

The testis produces the sperms by the process of gametogenesis. The sperms along with the semen are ejaculated through the urethra of the penis. The penis is made of smooth muscles. During ejaculation, the penis gets erect. At the time of sexual stimulation, the blood vessels of the soft tissues of the penis undergo vasodilation, and blood fills the blood vessels post which vasoconstriction occurs. This helps to keep the penis erect for ejaculating the sperm and the semen.

Option d. is given as “seminiferous tubules”.

As penis erection is achieved with the help of spongy tissue of the penis filled with blood, the correct answer is option d.

Reasons for incorrect statements:

Option a...

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