Sexual Reproduction and Meiosis - Mr. Aitken's Biology Class

[Pages:78]Sexual Reproduction and Meiosis

Ultrasound: ? Chad Ehlers/Glow Images Copyright ? McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.

Why Sex?

Reproduction occurs in two main forms: asexual and sexual.

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

In asexual reproduction, an organism replicates its DNA and splits the contents of one cell into two. This amoeba is reproducing asexually.

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

Asexual reproduction generates nearly identical offspring.

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

In sexual reproduction, the DNA of the offspring comes from two parents. Humans, cats, and many other familiar organisms reproduce sexually.

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

A female parent contributes an egg, and a male parent produces sperm. These cells fuse, yielding the first cell of the next generation.

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

But attracting a mate and producing sex cells are costly. Why is sexual reproduction so common?

Section 9.1

Human family: ? Corbis RF; Amoeba reproducing by binary fission: ? Carolina Biological Supply Company/Phototake; Mother cat and kittens: ? Jane Burton/Dorling Kindersley/Getty Images

Figure 9.1

Why Sex?

Sexual reproduction produces genetic diversity among offspring, which increases the chance that some offspring survive in changing environments.

Section 9.1

Figure 9.2

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