Download Asexual and Sexual Reproduction PPT

Chapter 7
Sexual Reproduction and the
Diversity of Life
Mrs. McLean – Science 300
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
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
Meiosis Review
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)
Parts of the Flower
Draw and copy this chart into notes
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
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
Be prepared to label the parts of the
cell as seen on page 210 in the
textbook (study the diagram)
Do questions 1-6 on page 209
Homework
Read section 7.5, pages212-213
Do questions 1-4 on page 213
Answers to 7.3 Questions
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 makes its
way to the female egg cells. This process
is called fertilization. The fertilized eggs
become seeds which grow a new plant.
7.3 Answers continued
4. Once fertilized, the ovary becomes larger
and grows into the fruit.
5. Seeds (b&c) have spikes that get
entangled with animal fur. A & D have
large surfaces that catch the wind. E has a
parachute that catches the wind.
6. Since the fruit is usually appetizing, the
animals eat the fruit and the seeds get
dispersed.
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
Reasons for selective breeding,
crossbreeding, cloning, grafting, and
genetically engineered (modified) plants
Higher crop yield
Better disease resistance
Better nutritional quality
Improved flavour
Development of traits that are useful fro
storage, shipping and processing
Monocultres
Def’n: When large areas of
agricultural land are planted with just
one variety of food crop Irish Potato
Famine
People’s dependency can cause mass
deaths or emigration
Increased use of fertilizers
HW- #1-3 on page 213
Answers to #1,2,3 on Page 213
1. As the world population continues
to increase, food production must be
increased or many 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. Since
fertile land is limited, farmers can get
better yields by growing grafts.
Answers continued
3. Clones produce exact duplicates of
the parent plants. In grafting, a
section from one plant is attached to
another. The grafted plant and the
host plant do ot exchange genetic
information.