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SBI3U
Oct 6, 2014
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Agenda: Oct 7th
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6:30-6:45. Study for quiz/ questions
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6:45- 7:10 Quiz #2
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7:15-8:45
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Collect money for workbooks
Take up Dichotomous Key Example
Hand back Quiz #1 and take up
Unit Test on Diversity: Tuesday*
Review on Thursday
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Ebola Research assignment: www.sbi3utaylor.weebly.com
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Due TUESDAY
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Retrovirus: A virus that is composed not of DNA but of RNA.
Retroviruses have an enzyme, called reverse transcriptase,
that gives them the unique property of transcribing their RNA
into DNA after entering a cell. The retroviral DNA can then
integrate into the chromosomal DNA of the host cell, to be
expressed there. HIV is a retrovirus.
UNIT 1 Chapter 2: Diversity: From Simple to Complex
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Bacteria, Human Health, and
the Environment
Some bacteria can harm human health.
Examples include:
• Clostridium botulinum causes
food poisoning
• Streptococcus pyogenes
causes strep throat
• Streptococcus mutans causes
tooth decay
Section 2.2
UNIT 1 Chapter 2: Diversity: From Simple to Complex
Section 2.2
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Bacteria, Human Health, and
the Environment
Bacteria are decomposers. They break down organic
molecules and release carbon, hydrogen, nitrogen, and sulfur,
thereby supporting those nutrient cycles. Through the process
of photosynthesis, cyanobacteria are major producers of
oxygen gas on Earth.
Some species in Archaea have enzymes that are of special
use to humans because they can withstand extreme
temperatures, salinity, and acidity. Biotechnologists have
been able to use some of these enzymes for various
procedures in DNA research.
UNIT 1 Chapter 2: Diversity: From Simple to Complex
Section 2.3
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2.3 Eukaryotic Evolution and Diversity
About 2 billion years ago, eukaryotes evolved and this led to
an increase in the diversity of life on Earth.
These organisms are more complex than prokaryotes. They
include more genes, allowing for greater cellular diversity in
terms of size, shape, mobility, and specialized functions.
Scientists examined the important question of how eukaryotic
cells evolved and have come up with some theories supported
by observations and evidence.
UNIT 1 Chapter 2: Diversity: From Simple to Complex
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Section 2.3
Endosymbiosis
The theory of endosymbiosis suggests that eukaryotic cells
evolved from symbiotic relationships between two or more
prokaryotic cells
Although one prokaryotic cell engulfed a different, simpler
prokaryotic cell, the engulfed cell survived and became
part of the host cell.
UNIT 1 Chapter 2: Diversity: From Simple to Complex
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Chloroplasts and Mitochondria
Chloroplasts and mitochondria may have
been free-living prokaryotes engulfed by
larger prokaryotes. They continued to
perform their cellular activities while
surviving and serving the host cell. A
comparison of chloroplasts, mitochondria,
and prokaryotes shows:
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similar types of membranes
similar types of ribosomes
each reproduces by binary fission
each contains circular chromosomes
gene sequences match
Section 2.3
UNIT 1 Chapter 2: Diversity: From Simple to Complex
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Section 2.3
Multicellularity
Based on fossil evidence, scientists think that large, complex
eukaryotes first developed about 550 million years ago. They
have also found fossils of simple red algae in the Arctic that
date multicellular eukaryotes as far back as between 1.2 and
1.5 billion years ago.
Scientists hypothesize that the first multicellular organisms
arose from colonies created by individual cells that divided.
Genes within these cells contained
instructions for some cells to
become specialized. With the
passage of time, groups of cells
developed different functions.
UNIT 1 Chapter 3: Multicellular Diversity
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Chapter 3: Multicellular Diversity
The multicellular world is grand and diverse. Yet, human factors are
continually having negative consequences on the species, including
decreasing species and genetic diversity. The eastern massasauga
rattlesnake, found in Ontario, is experiencing great habitat loss.
How do you think ecologists
study habitat loss for the eastern
massasauga rattlesnake?
Section 3.1
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.1
3.1 From Algae to Terrestrial Plants
Some scientists classify multicellular green algae in the plant kingdom; others
classify it in the protist kingdom. Clearly, it is not always easy to classify a
species. However, scientists do agree that green algae represent the
evolutionary link between protists and plants.
To continue the investigation of life’s diversity, a closer look at the brown
(phylum Phaeophyta), red (phylum Rhodophyta), and green algae (phylum
Chlorophyta) is useful.
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.1
Green Algae
Phylum Chlorophyta species live in diverse habitats, including
freshwater, saltwater, sea ice, tree surfaces, and even in the fur of sloths!
They are equally diverse in structure, with unicellular and
multicellular representatives. However, all resemble
plants—their cell walls are comprised of cellulose and
genetically similar chlorophyll molecules.
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.1
The Shift to Land
Evidence suggests that green algae and land plants are related.
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Both contain chlorophylls a and b.
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Both have cellulose-based cell walls.
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Both store food as starch.
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They have shown genetic similarities.
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Green algae use a number of reproductive strategies, such as sexual sporic
reproduction, that some plants use as well.
The first terrestrial plants were small, limited by the speed of
diffusion to transfer water and dissolved substances throughout the
plant.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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The Shift to Land
Many changes over long periods of time occurred in the
evolution of plants. In this time, early plants evolved to
reproduce with embryos.
Section 3.1
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.1
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Vascular Tissue, Leaves, and Roots
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Early terrestrial plants lacked tissues that could transport materials over large
distances. Eventually, such tissues evolved and vascular plants emerged.
Phloem tissue transports sugars.
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Xylem tissue transports water and minerals. It also enables plants to grow
to great heights since the transport tubes are fortified with tough lignin.
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Lignin is also incorporated into the root system to anchor larger plants and aid
absorption.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.1
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Vascular Tissue, Leaves, and Roots
Leaves evolved as specialized
structures to maximize the
capture of light energy.
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.2
3.2 The Plant Kingdom
The organization of the plant kingdom is based on some fundamental characteristics,
including the presence or absence of vascular tissue and seeds.
The plant kingdom can be studied from the simple to the complex; from non-vascular,
seedless plants to vascular plants with seeds.
The following seedless phyla will be highlighted:
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UNIT 1 Chapter 3: Multicellular Diversity
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Non-vascular Plants
All seedless, non-vascular plants are referred to as
bryophytes, although only the mosses are actually in
Phylum Bryophyta. Liverworts and hornworts are also
non-vascular bryophytes but in different phylums
They are all dependent on diffusion and osmosis to
transport nutrients and waste. They attach to the ground
with rhizoids and remain low to absorb water.
They are early terrestrial plants and provide important
ecological services, including nutrient cycling.
Section 3.2
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.2
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Seedless Vascular Plants
Once plants evolved the ability
to transport nutrients through
specific tissues, their height
increased.
Ex. Ferns, club mosses
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.2
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Seed-producing Vascular Plants
There are two distinct groups of seed-producing plants:
gymnosperms and angiosperms. Gymnosperms have nonenclosed seeds, while angiosperms enclose their seeds in
protective tissue. Reproduction with seeds is useful to plants
because they:
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allow sexual reproduction without water
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provide protection for the embryo
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can survive for many years without water
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can survive colder temperatures
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can be dispersed away from the parent plants
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.2
Gymnosperms
Most are evergreen and perform photosynthesis year-round.
Gymnosperms often inhabit environments that are too dry,
cold, or hot for angiosperms.
(A) Coniferous trees produce
seeds on the surface of cone
scales, making them a target for
animals such as birds.
(B) Cycadophytes are short,
palm-like trees with scaly trunks,
but they are not closely related
to palms.
(C) Ginkgo biloba is the only
living species in the ginkgophyte
group.
The soft male cones of gymnosperm produce pollen (gametophytes). The harder female cones
produce eggs that are exposed on the surface of cone scales. The wind carries the pollen to fertilize
the eggs.
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.2
Angiosperms
The angiosperm group is also extremely diverse and includes
over 250 000 species. Known as the flowering plants, they
protect their seeds in fruits and reproduce using flowers. They
also use pollen grain gametophytes to carry the male gamete
to the egg, which is situated deep in the flower.
Angiosperms include most nonconiferous trees, such as (A)
birch trees, showy flowers such
as (B) prairie roses, and food
crops such as (C) wheat. All use
flowers to produce enclosed
seeds.
Other examples include trilliums, maples, oaks, and grasses.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.2
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Angiosperms
Fruits are also specialized structures for seed protection. They
range in morphology to disperse seeds successfully. Some:
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attract animals that eat them and then excrete the seeds in a different location
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are adapted for sticking to fur
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are protective enclosures for seeds that are dispersed by water
Seeds are dispersed
through different
types of fruits.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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The Fungus Kingdom
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This kingdom has more than 100 000 species, ranging from
unicellular to multicellular. They all contain chitin in the cell
walls.
The visible body and underground structure of a multicellular
fungus is made of hyphae. Under suitable conditions, the
fungus produces a fruiting body that produces airborne
spores.
Section 3.3
UNIT 1 Chapter 3: Multicellular Diversity
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Fungal Nutrition
All fungi are heterotrophs.
However, they digest
externally by releasing
enzymes and then absorbing
the digested nutrients. They
can do this by being
parasitic, predatory,
mutualistic, or saprobial
(feeding off dead organisms
or organic waste).
Section 3.3
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.4
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3.4 The Animal Kingdom
While 35 phyla make up this rich kingdom, most animals are
worms. However, all animals share some characteristics:
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eukaryotic and multicellular
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no cell walls
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heterotrophic
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mobile in at least one stage of life
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reproduce sexually
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produce an embryo that develops
into the significant life stage
About 95 percent of animals are invertebrates.
(A) Sponges live in aquatic environments, attached to
solid surfaces such as rocks, coral, or the shell of
another animal. (B) Sea anemones use their stinging
tentacles to catch food. (C) Sea cucumbers feed on
dead and decaying matter.
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.4
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Vertebrate Animals
The 50 000 species in this phylum, called phylum Chordata, are
divided into five major classes: fish, amphibians, reptiles, birds,
and mammals.
All chordates have two common features that extend the length
of the body:
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a notochord: a flexible, rod-like structure (replaced by a spine in
vertebrates)
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a dorsal nerve cord
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.4
Vertebrate Animals
Most chordates have an endoskeleton made of bones. Some have
only cartilage that is flexible but tough. Some are aquatic; some
are terrestrial. Some are known as tetrapods as they have two
pairs of limbs.
What characteristics indicate pigs belong in phylum Chordata?
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.4
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Vertebrate Animals
Class Amphibia evolved from bony fish as fins changed into
limbs over time. Amphibians are tetrapods and include frogs,
toads, and salamanders. They are dependent on wet or moist
habitats to survive. Human activity has had a devastating effect
on many species in this class.
In Ontario, there are
representatives of the
two major amphibian
orders. The bullfrog (A)
is an anuran (frogs and
toads), and the spotted
salamander (B) is a
urodelan (salamanders
and newts).
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.4
Vertebrate Animals
The Reptilia class is younger than the amphibian class, with
fossils dating back “only” 300 million years. Three orders exist:
lizards and snakes, turtles, and crocodilians.
In the three orders, the four
major groups of living
reptiles are the snakes,
lizards, turtles, and
crocodilians. The eastern
foxsnake (A), five-lined
skink (B), and wood turtle
(C) are all Ontario
residents. The gavial (D) is
an endangered species on
the Indian subcontinent.
Reptiles are not dependent on wet ecosystems because they have
evolved body scales that prevent dehydration. They use lungs for
gas exchange. Fertilization is internal, and while most lay eggs,
some reptiles in colder environments give birth to live offspring.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.4
Vertebrate Animals
The bird group is called class Aves and may in fact be a
modified group of some of the extinct dinosaurs. Some dinosaurs
had feathers, like modern birds, while birds have scaled legs,
akin to the dinosaurs. Birds are all tetrapods. However, there are
important differences.
(A) Black-capped chickadees are
small songbirds whose range
covers parts of Canada and the
United States. (B) Ostriches are
large birds that do not fly. They
live in desert and grassland
regions of Africa.
Bird structural and habitat diversity is great. They appeared in
the fossil record about 150 million years ago. Most have hollow
bones that make them light enough to fly.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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Vertebrate Animals
Members of class Mammalia have the following distinctive
features:
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mammary glands that
secrete milk to nourish
young
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hair
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four-chambered hearts
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highly developed brains
Section 3.4
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.5
3.5 The Biodiversity Crisis
A simple equation expresses the impact of human population growth on
diversity:
human overpopulation + development =
accelerated extinction rate + biodiversity crisis
Biodiversity models lead many ecologists to believe the current extinction rate
matches past mass extinction levels, when large percentages of all living
organisms died within a short time. Current threats are:
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habitat destruction
competition from invasive species
illegal trade
pollution
climate change
Without biodiversity, ecosystems become unsustainable.
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.5
Impact of Climate Change
Food Source Decline
For example, caribou and reindeer populations are dropping
drastically (60% lower in 30 years) due to a lack of food such as
lichens and young plants. Foraging has been reduced due to:
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warmer winters and summers, which mean there are fewer lichens, and they
are harder to reach
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earlier springs mean plants are less nutritious by the time the migrating
animals arrive in the area
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.5
Impact of Climate Change
Disruption of Reproduction
For many species, including the tuatara and the Ontario turtles, environmental
temperatures determine the sex of the offspring. Warmer temperatures mean
there is an imbalance in male-female ratios.
The tuatara (Sphendon punctatus) is
sometimes referred to as a living dinosaur.
Although it looks like a lizard, its closest
relatives are an extinct group of reptiles that
lived about 200 million years ago, during the
time of the dinosaurs.
Pollination Failure
While both animal pollinators and plants may start seasonal growth and
development earlier due to warmer temperatures, their growth cycles may no
longer match. This results in less pollen food for the animal forager, which in
turn leads to fewer animal foragers around when the plant reaches its
pollination peak. The result is a decline in population for both species.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
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Section 3.5
Impact of Climate Change
Habitat Decline
Snow-bed plant communities on mountain-tops are adapted for flowering in the
summer and surviving the winter snow. However, their habitat is small and
plants living below them are moving up the warming mountain-tops. This leads
to smaller populations of snow-bed plants and less genetic diversity.
As temperatures
increase, the vegetation
zones in mountainous
regions shift. Upper
zones become smaller
and may even be
eliminated.
Continued…
UNIT 1 Chapter 3: Multicellular Diversity
Section 3.5
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Impact of Climate Change
Aquatic Ecosystems
When the temperature of an aquatic environment rises, some
important changes occur:
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invertebrate growth rate is increased,
but population density is decreased
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male-to-female ratio changes in some species
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the appetite and feeding patterns of some
species are altered
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fish growth rate decreases
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fish consume more oxygen