Chapter 17: Problem 12

Only one sperm enters an egg because a. sperm have an acrosome. b. the corona radiata gets larger. c. changes occur in the zona pellucida. d. the cytoplasm hardens. e. All of these are correct.

Short Answer

Expert verified

The correct answer is option c - changes occur in the zona pellucida. These changes prevent other sperm cells from entering the egg and ensure that only one sperm cell fuses with the egg during fertilization.

Step by step solution

Understand the Fertilization Process

Fertilization is the process where a sperm cell fuses with an egg cell to form a zygote, the first cell of a new organism. Several sperm cells reach the vicinity of an egg cell, but only one is able to penetrate and combine its genetic material with that of the egg. The other sperm cells are prevented from entering due to certain changes that occur in the egg's structures. Now, let's analyze each given option:

Option a - Sperm have an acrosome

The acrosome is a structure present at the head of a sperm cell. It contains enzymes that help the sperm penetrate the egg's outer layers. While the acrosome is important for the sperm to reach the egg, it does not explain why only one sperm enters the egg.

Option b - The corona radiata gets larger

The corona radiata is a layer of cells surrounding the egg, providing nutrients and support. Changes in the size of the corona radiata do not play a role in preventing multiple sperm from entering an egg.

Option c - Changes occur in the zona pellucida

The zona pellucida is a glycoprotein layer that surrounds the egg's plasma membrane. When a sperm cell penetrates an egg, changes called the cortical reaction occur in the zona pellucida. These changes, also known as the zona reaction, involve the release of enzymes that modify the zona pellucida, making it impermeable to other sperm cells. This is the main reason why only one sperm enters an egg.

Option d - The cytoplasm hardens

The cytoplasm is the cell's internal material, and although it undergoes some changes during fertilization, it does not harden. Therefore, this option doesn't explain why only one sperm enters an egg.

Option e - All of these are correct

Since option c is the only correct answer, the option that states all of them are correct is not accurate.

Conclusion:

The correct answer is option c - changes occur in the zona pellucida. These changes in the zona pellucida prevent other sperm cells from entering the egg and ensure that only one sperm cell fuses with the egg during fertilization.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Biology Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Only one sperm enters an egg because a. sperm have an acrosome. b. the corona radiata gets larger. c. changes occur in the zona pellucida. d. the cytoplasm hardens. e. All of these are correct.

Short Answer

Step by step solution

Understand the Fertilization Process

Option a - Sperm have an acrosome

Option b - The corona radiata gets larger

Option c - Changes occur in the zona pellucida

Option d - The cytoplasm hardens

Option e - All of these are correct

Conclusion:

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Biology Textbooks

Biological Processes

Ecological Levels

Cell Cycle

Organ Systems

Plant Biology

Energy Transfers

Study anywhere. Anytime. Across all devices.