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Chapter 7
Sexual Reproduction and the
Diversity of Life
Ways of Reproduction
Reproduction
Asexual
Sexual
Binary Fission
Hermaphroditic
Budding
Separate Sexes
Fragmentation
Conjugation
Spore Formation
Vegetative Rep.
The Difference Between
Asexual and Sexual
 Asexual Reproduction – a single cell ( the
mother cell) duplicates the same genetic
information and becomes two daughter
cells.
 Sexual Reproduction – genetic information
from two cells is combined to form the new
genetic code for a new organism.
Sexual Reproduction
Types: Conjugation, Hermaphrodites, Separate Sexes
Conjugation – two cells come together
and exchange small pieces of their genetic
information (bacteria)
 Hermaphrodites – organisms that create
both male and female sex cells. Occurs in
organisms that have restricted movement
(sponges)

Sexual Reproductions
continued
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Separate Sexes – In complex organisms
specialized sex cells (sperm and egg)
combine to form a zygote. Offspring are
not identical to either the parent or further
offspring
(humans and some plants)
Fertilization
Fertilization
External- a process
where male sperm
cells are combined
with female egg
cells outside
the female’s body
(fish)
Internal- a process in
the male sperm is
united with the female
egg inside the
female’s body
(humans)
Homework

Read Section 7.1, pages202-205

Do questions 1-6 on page 205
Answers to 7.1
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1. A zygote is a fertilized egg.
2. Conjugation is a genetic recombination mechanism.
3. Animals that contain both male and female sex cells
are referred to a hermaphroditc. Sponges, tapeworms,
earthworms, and barnacles are both male and female.
4. a) internal fertilization: mammals, birds, earthworm
B) external fertilization: fish, amphibians, invertebrates
5. Females contain two X chromosomes, while males
contain a single X and a Y.
6. a) 11 b) 22
c) 22
d) 11
Meiosis
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The process of forming
sex cells,
A human body cell
contains 23 pairs of
chromosomes. The
gametes - sperm or
eggs - contain half this
number of
chromosomes, which is
why meiosis is
sometimes called
'reduction division'.
Meiosis continued
Organisms that reproduce sexually contain
2 types of cells.
 1) Somatic- cells that reproduce by
mitosis, when cells divide each daughter
cell is identical as the mother cell (skin
and muscle cells
 2) Reproductive- produce sex cells which
only have half the number of
chromosomes (haploid cell)

Meiosis
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View video link http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=s
wf::535::535::/sites/dl/free/0072437316/1
20074/bio19.swf::Stages%20of%20Meio
sis

Draw stages of meiosis into your
notebooks (page 206/7 from textbook)
Homework

Read section 7.2, pages 206-207

Do questions 1-8 on page 207
Answers to 7.2 Questions
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1. Somatic have a full compliment of
chromosomes (diploid). Reproductive cells
have one of the pairs of homologous
chromosomes (haploid cells).
2. Chromosomes that are simiar in size,
shape, and gene arrangement are
homologous.
3. Meiosis 1 is the reduction division phase
and Meiosis 2 is the division of the double
stranded chromosomes.
Answers continued
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4. Comparison of Mitosis and Meiosis
Mitosis
Meiosis
One division
Two divisions
Two cells produced
Four cells produced
Cells are identical
Cells contain half the
chromosome of a parent
5. Meiosis reduces the chromosome number in
sex cells from diploid to haploid.
6. 39 chromosomes
7. Yes they have the same number.
8. Genes code for the same characteristic but
they may not be identical.
Parts of the Flower
Use diagram as reference to part descriptions on next slide
The Male Parts
 Pollen – the male sex cells of the flower
 Filament - This is the stalk of the Anther.
 Anther - The Anthers contain pollen sacs.
The sacs release pollen on to the outside of
the anthers that brush against insects on
entering the flowers.
* The filament and the anthers are collectively
known as the Stamen
The Female Parts of the Flower
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Egg the female sex cells of the flower
Stigma Is covered in a sticky substance that
the pollen grains will adhere to.
Style The style raises the stigma away from
the Ovary to decrease the likelihood of pollen
contamination.
Ovary This protects the egg and once
fertilization has taken place it will become the
fruit.
Homework

Read section 7.3, pages208-209
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Be prepared to label the parts of the cell as
seen on page 210 in the textbook
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Do questions 1-6 on page 209
Answers to page 209
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1. Flowering plants contain both male and
female sex cells.
2. Male sex cell (pollen) and female sex cell
(eggs).
3. During reproduction, the pollen sends a
sperm down through the pistil with the male
gamete in it. The sperm makes its way to
the female sex cells in a process called
fertilization.
Answers Continued
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4. Once fertilized, the female sex cells of the
flower become seeds. The petals of the flower
slowly shrivel and disappear. The surrounding
ovary becomes larger and develops into the
fruit.
5. Seeds (b,c) have spikes that get entangled
in animal’s fur. Maple and poppyseed have
large flat structures that catch the wind.
Dandelions act as parachutes that get carried
by the wind.
6. Since the fruit is generally appetizing,
animals eat fruits and scatter the seeds via the
hind end.
Strategies for
Increasing Food Production
Strategies
Selective BreedingOffspring with the
same desired
characteristics
CrossbreedingPollen is taken from one
plant and fertilized with
the egg of another
Cloning
Grafting
Exact duplication
Sections of one plant
Is combined with
another
Homework

Read section 7.5, pages212-213
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Do questions 1-3 on page 213
Answers
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1. As the world population increases, food
production must increase or people will starve.
2. Grafting allows a tree to produce a different
type of fruit quickly. Selective breeding identifies
plants with the most desirable traits.
3.In both cloning and grafting no sexual
reproduction takes place so no new combination
of genes will take place; therefore no diversity
Atypical Meiosis
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Atypical meiosis is the term given when
meiosis does not separate the chromosomes
correctly.
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Nondisjunction is the failure to separate two
homologous chromosomes
* Understand Figure 1 on page 222
Nondisjuction
Video
Nondisjunction Orders
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Down Syndrome: too many chromosomes,
mental disabilities (47)
Turner Syndrome: too few chromosomes,
females don’t mature sexually/shorter (45)
Klinefelter Syndrome: too many
chromosomes, males cannot reproduce (47)
Homework

Read section 7.9, pages 222-223
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Do questions 1-5 on page 223
Chapter 7 Review
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Do questions 3-13 on pages 228-229
Answers to Chpt. Review Questions
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3. Sexual reproduction causes the recombination
of genetic info from different organisms. The new
combination of genes can produce new traits.
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4. a) asexual b) sexual c) sexual d) asexual
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5. Because only one chromosome pair from each
parent combines is a fertilized egg, different
children, formed by different sperm and egg cells,
will have new gene combinations.
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6.
Description
Produces 4 cells
Meiosis
Mitosis
X
Daughter cells are clones of
mother cell
Haploid cells produced
X
X
Skin cells
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X
Formation of sex cells
X
Two stages of cell division
X
7. The sperm cells unite with the female sex
cells in a process called fertilization. The
fertilized cells become seeds which in turn grow
new plants.
8. Male- pollen, anther and filament
Female- stigma, style, ovary
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9.
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10. a) female A b) 9,8,7 respectfully
c) fertilization d) zygote
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11. a) 23 b) Meiosis occurred c) 46
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12. a) stage 2 b) fertilization
23 pairs
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13 Genetic information from two different
individuals is combined. This creates genetic
diversity.
c) mitosis d)