CHAPTER 2
LESSON 1
REPRODUCTION
WHERE DO LIVING THINGS COME
FROM?
• Living things come from other living things.
• Every organism comes from a parent organism
through the process of reproduction.
REPRODUCTION
• Reproduction involves the transfer of genetic
material from parent to offspring.
• The genetic material contains information that
controls how the new organism will look and
function.
TWO MAIN TYPES OF REPRODUCTION
• Sexual reproduction
is the production of
a new organism
from two parents.
• Asexual
Reproduction is the
production of a
new organism from
a single parent.
SEXUAL AND ASEXUAL
REPRODUCTION
• What type of reproduction involves
only one parent?
• Asexual reproduction
• Which type of reproduction requires
fertilization?
• Sexual reproduction
THINK ABOUT IT…
• What type of reproduction produced
the young spider plants?
• Asexual reproduction
• Why do the lion cubs look similar to
their parents?
• During sexual reproduction, they
received traits from both parents.
ASEXUAL REPRODUCTION PRODUCES AN EXACT COPY OF THE
PARENT ORGANISM. WHEN COULD THIS BE A DISADVANTAGE?
QUESTIONS…
• This could be a disadvantage
if the parent organism does
not have desirable traits.
ASEXUAL REPRODUCTION
• There are several methods of asexual reproduction
shared by a wide variety of organisms.
• Organisms that reproduce through asexual
reproduction produce genetic copies of the parent
organisms.
• Methods
•
•
•
•
Splitting
Budding
Other forms without fertilization
Vegetative Propagation
METHODS OF ASEXUAL
REPRODUCTION
SPLITTING
• Most unicellular protists and bacteria reproduce by
splitting into two cells.
• First the organism copies its own genetic material.
• The two new offspring organisms will then each
have a copy of the genetic material they need to
carry out life processes.
• Some bacteria can divide into two new organisms
every 10-20 minutes.
BUDDING
• Cnidarians, sponges, and some fungi reproduce by
budding.
• The process of budding:
• A small part of the parent’s body grows into a tiny
and complete version of the parent. Sometimes,
the bud breaks off from the parent organism and
continues to grow. Other organisms, such as coral,
the newly formed bud remains attached to the
parent.
OTHER FORMS OF ASEXUAL
REPRODUCTION
• Fish, insects, frogs, and lizards reproduce without
fertilization taking place.
• The females produce egg cells, but the egg cells
are not fertilized. They develop into a new animal
without fertilization.
• Queen bees- Some of their eggs are fertilized and
some are not. The fertilized eggs develop into
females, or worker bees. The unfertilized eggs
become males, or drone bees.
VEGETATIVE PROPAGATION
• A form of asexual reproduction in plants that
produces new plants from leaves, roots, or stems.
• Runners are plant stems that lie on or under the
ground and sprout up as new plants.
• Strawberry plants, ferns, and most grasses
reproduce by growing runners.
HOW DO YOU KNOW THAT THE OFFSPRING FROM
ASEXUAL REPRODUCTION WILL BE EXACTLY LIKE
THE PARENT?
• They inherit the genetic
material of the parent. They
have the same traits as the
parent.
• http://mrsdlovesscience.com/asexualrepro.html
LOOK AT THE IMAGES OF SPLITTING
AND BUDDING ON P. 92.
• What is the most important difference between the
processes?
• Splitting occurs as single-celled organisms split into
two cells. Budding involves a small part of the
parent’s body that grows into a new individual.
QUESTIONS…
• Describe the steps in bacteria reproduction.
• First, the organism produces a copy of its genetic
material. Next, the organism splits into two new
individuals.
WHAT IS THE DIFFERENCE BETWEEN
A DRONE AND A WORKER BEE?
• A drone is a male bee and develops
from an unfertilized egg. A worker bee
is female and develops from a
fertilized egg.
WHAT PART OF THE STRAWBERRY PLANT
CAN PRODUCE NEW PLANTS WITHOUT
SEEDS?
•The stem
LET’S READ PGS. 94-95.
• What do all seeds need to germinate?
• Water
• Soil
• Warm temperatures
WHAT DO YOU THINK IS INSIDE SEEDS?
• No matter what size the seed is, they all contain a
small embryo plant surrounded by a food supply.
• Why do you think seeds have a seed coat?
• To protect them
WHAT IS THE FUNCTION OF THE FRUIT?
• It protects the seed.
HOW DOES A BIRD’S EGG PROTECT THE
EMBRYO DEVELOPING INSIDE?
• The shell keeps the embryo from drying out. The yolk
provides food for the developing embryo.
SEED COAT
• What do you wear to protect you from cold,
wind, rain, or snow?
• A coat
• Just like your coat protects you, the coat on
a seed protects the seed from the
environment.
HOW IS A FISH OR AN AMPHIBIAN EGG
PROTECTED?
• By a jelly-like layer that surrounds the egg.
Fish Eggs
Frog Eggs
GERMINATION OF A SEED
• Describe the sequence of events that lead to the
germination of a seed.
• A seed is produced. The seed develops and falls
from the parent plant. Wind carries the seed to a
new location. The seed will germinate if conditions
are right for growth.
• A volcanic island in the ocean has no
plants growing on it. Soon seed plants
appear. How might these seeds have
reached the island?
• Seeds could have blown there with
wind, floated there as fruits or seeds in
the water, or been carried there by
animals.
LET’S READ PGS. 96-97.
• Yeast are fungi that reproduce
through budding. Other fungi can
reproduce asexually by producing
spores. Some fungi also reproduce
sexually.
WHAT IS A SPORE?
• A reproductive cell that is produced through cell
division. When conditions are right, a spore can
produce a new organism.
WHAT ARE FRUITING BODIES?
• Reproductive structures of some fungi that
produce spores
HOW ARE MUSHROOM SPORES
DISPERSED?
• Some spores are dispersed by the wind;
others are dispersed by insects.
YEAST PRODUCTION
• Describe the steps in yeast reproduction.
• Yeast reproduce through budding. Budding begins
when a small growth forms on the parent cell. The
nucleus divides into two. One of the two nuclei
become part of the bud. The bud finally breaks off
and lives as a new organism.
STINKHORNS ARE FUNGI THAT SMELL LIKE
ROTTING MEAT. HOW COULD THIS
CHARACTERISTIC HELP THESE FUNGI DISPERSE
THEIR SPORES?
• If a stinkhorn fungus smells like rotting meat, it may
attract insects. When an insect comes in contact
with a stinkhorn fungus, the spores may stick to it.
The spores may be dispersed in a new location
when the insect flies away.
ASEXUAL AND SEXUAL
REPRODUCTION DIFFERENCES
• Asexual
Reproduction:
• only one parent
• offspring identical
to the parent
• Sexual
Reproduction:
• two parents
• Offspring have a
combination of the
parents’ traits
WHY IS IT AN ADVANTAGE FOR AN
ORGANISM TO BE THE PRODUCT OF SEXUAL
REPRODUCTION?
• It provides variety in the offspring
and in a species. Offspring might
be better suited to environmental
changes than the parents.
HOW CAN YOU TELL THAT THESE PUPPIES ARE NOT
THE RESULT OF ASEXUAL REPRODUCTION?
• The puppies all look different, which means they
have traits from both parents. They are the result of
sexual reproduction.
DESCRIBE THE SEQUENCE OF EVENTS THAT COULD
HAPPEN TO A MOUSE POPULATION IF ORGANISMS
THAT EAT MICE MOVED INTO THEIR HABITAT?
• Organisms that eat mice appear. The slow
mice get eaten. The fast mice survive and
reproduce. The mouse population then
changes to mostly fast mice.
WHAT IS AN ADVANTAGE OF ASEXUAL
REPRODUCTION?
• Asexual reproduction can occur
without a mate.