Transcript - PlanbookConnect

Cool organism of the day…
Common Cuckoo
•The cuckoo doesn’t raise it’s own babies
•It is a parasite that lays eggs in another bird’s nest.
•The baby cuckoo pushes the eggs out of the nest!
•The other bird feeds the cuckoo chick – even though
the cuckoo soon grows to be 2 or 3 times its size!
Variations
-are the differences in characteristics
of organisms
-can be caused by genetic and
environmental factors
-these are the differences within the
same species and the differences
among species
Variation within a Species
• there can be differences between
members of the same species
• these differences better enable an
organism compete for a food source or
compete to reproduce
• there can be variations in:
o size
o colour
o food source
obehaviour
o body parts
o feet, ears
What is a species?
Organisms can be grouped as a
species if:
1) They interbreed in nature.
2) Their offspring are able to
breed.
Variations for Survival
•plants and animals adapt to better
compete for resources
•the animals that have the best
variations get the most food, grow
bigger, get stronger, and win the
right to reproduce
Structural Adaptation
these are the physical features and
characteristic of a plant or animal to help
it compete for resources and survive
Examples:
colour, eyes, horns, feet, fur, thorns
Behavioural Adaptation
•these are the activities and behaviours
of an animal to help it better compete or
survive
Examples:
mating, migration, hunting, nest building
What are adaptations?
• Adaptations enable an organism to
compete for survival and reproduce
in the environment.
Competition
• can occur between different species and can
also occur between members of the same
species
• species compete for food, resources, and
shelter
• the organism that has the best adaptations
will win the competition
• the organism that wins the competition gets
to reproduce
Generalist
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is an organism that lives in a broad niche
can live in a variety of climates/ecosystems
can eat a variety of food sources
is able to adapt to changes in the ecosystem
cannot compete as well with a specialist for
the same food source
Examples:
deer, coyote, raven
Specialists
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is an organism that lives in a narrow niche
can only exist in a specific climate/ecosystem
only eats a specific food source
cannot adapt to change
Examples:
Panda, koala, cactus
Symbiotic relationships
• dependence between species
Almost no organisms can survive on their own.
Even you! For every one human cell there are 10
bacteria cells in your body!!
Without bacteria you wouldn’t
be able to digest food!
Commensalism
• two organisms that live in direct contact
with each other, neither is harmed
Example: - barnacle and whale
Mutualism
• the relationship benefits both species
Example:
- plant root and mycorrhizae (fungus)
Parasitism
• the relationship harms one organism and
benefits the other
Example:
- malaria (mosquito, human)
Malaria (protist)
Asexual Reproduction
• there is only one parent
• the DNA of the offspring is identical to
the parent (clone)
• there is little possibility for variation or
adaptation
• if the ecosystem or climate changes a lot,
the organism is unable to adapt
• many off-spring can be produced quickly
Forms of Asexual Reproduction
• Binary Fission - bacteria, amoeba
(single-celled organism)
• One cell duplicates all its contents
• The cell divides into 2 “daughter”
cells
• The two cells have exactly the same
material
Mitosis
• human body cells have 46 chromosomes (23
pairs)
• the chromosomes are made up of our DNA
• body cells divide and reproduce in a process
like binary fission
• through mitosis each new body cell also has
46 chromosomes (23 pairs)
Sexual Reproduction
• this is how the genetic traits are passed on
from two different parents to the offspring
• Since both parents supply the genetic
material, the offspring will not be exactly
identical
• The offspring will display a combination of
characteristics from both parents
Sexual Reproduction
• provides opportunities for variation and
adaptation
• only those parents with the best adaptations
survive or compete to reproduce
• requires a lot of time and energy
• only a small number of offspring are produced
2) Bacterial Conjugation
• This is a primitive form of sexual
reproduction
• Two parent cells are involved
• The benefit is to produce new
combinations of inherited
characteristics
2) Bacterial Conjugation
• It results ONLY in genetic
recombination NOT reproduction
• There is no increase in the number
of cells
• Following conjugation, new cells are
produced by binary fission
(asexual)
Fertilization
• There are two types of fertilization
1) External fertilization – the fertilization occurs
outside the female
e.g. fish, amphibians (frogs), worms
2) Internal fertilization – the fertilization occurs
inside the female
e.g mammals, insects, reptiles, birds, some
fish and amphibians
Advantages of internal fertilization
• Internal fertilization can increase the success
of fertilization
• The egg cells are protected inside the body of
the female parent
• Sperm deposited by the male into the
female’s body moves directly towards the egg
so there are less risks to the survival of the
gametes
Fertilization
• If a mature egg is present, fertilization
can occur
• The egg and sperm join to form a zygote
• The zygote grows and divides many
times to become an embryo
• In most mammals the embryo grows
close to or inside the female’s body
Genetics
• genetics is the study of heredity (traits
passed on from parent to offspring)
• we inherit our traits from our parents
because of genetics
• we get half of our DNA from our mother
(23 chromosomes) and the other half
from our father (23 chromosomes)
There are two types of variation
I. Continuous Variation
• there are a wide variety of possible
outcomes
• these traits have a lot of “inbetween” possibilities
• Examples: weight, height, skin
colour, hair colour, eye colour
There are two types of variation
II. Discrete Variation
• there are a limited number of
possible outcomes
• there are NO “in-betweens” for
these traits
Dominant or recessive?
Dominant
• if a dominant and a recessive trait are both
inherited then the dominant trait will override the recessive trait
• Examples:
– Brown eyes (are dominant to blue eyes)
– Hitchhiker thumb(is dominant to straight thumb)
Dominant or recessive?
Recessive trait
• the recessive trait will be overpowered by a
dominant trait
• the off-spring will inherit a recessive trait only
if both parents pass on the recessive trait
• Examples:
– Blue eyes
– Straight thumb
Punnett Square
• A punnett square can be used to predict
how many offspring will get a certain
trait from the parents
• A dominant trait is represented by a
capital letter (e.g. brown eyes – B)
• A recessive trait is represented by a small
letter (e.g. blue eyes  b)
Punnett Square
Mother (brown eyes)
B
father
(brown eyes)
b
B BB
Bb
b Bb
bb
mother
B
father
b
B BB
Bb
b Bb
bb
offspring
BB – brown eyes (1/4)
Bb – brown eyes (1/2)
bb – blue eyes (1/4)
75% of offspring will have brown eyes
25 % of offspring will have blue eyes
Nature vs. Nurture
(genes vs. environment)
• Not all characteristics are inherited - some
characteristics are learned.
• Some of our behaviours are the result of our
environment.
• Examples:
– Personality
– Being a good athlete
– Weight, eating disorder
DNA
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DNA is the basic genetic material
DNA contains our genes
It is inside the nucleus of each cell
DNA is a long, complex molecule
shaped like a coiled ladder
Chromosomes
• The DNA in a cell is not just one
long/huge molecule.
• It comes in tightly coiled “packages”
called chromosomes
• humans have 46 chromosomes in
their cells
nucleus
cell
tissue
c
h
r
o
m
o
s
o
m
e
DNA
Cell replacement
Are chromosomes
copied?
Cells divide by a
process called:
yes
yes
Mitosis
meiosis
Genetically identical
to original
Genetically
different than
original
46
23
2
4
New cells are…
# chromosome in
new cells:
How many cells are
produced?
Formation of
gametes
(egg + sperm)
Artificial Selection
• these plants and animals have been bred
for specific traits
• variation can occur much quicker
because humans decide which
plants/animals will pollinate/mate
Selective breeding
• plants or animals that have the most
desirable traits are chosen to mate
• same as artificial selection
The theory of Natural Selection
• Charles Darwin went to the Galapagos Islands
• He observed a great deal of biological
diversity and tried to figure out an
explanation
• He talked to breeders and farmers
• Darwin came up with a theory of natural
selection to explain how a process like
artificial selection could happen in nature