Study Guide
Chapter 8 – The Energy of Life
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The living cell is a miniature chemical factory where thousands of reactions occur
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The cell extracts energy and applies energy to perform work
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Some organisms even convert energy to light, as in bioluminescence
An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics
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Metabolism is the totality of an organism’s chemical reactions
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Metabolism is an emergent property of life that arises from interactions between molecules
within the cell
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A metabolic pathway begins with a specific molecule and ends with a product
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Each step is catalyzed by a specific enzyme
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What is the role of metabolic engineering and why is it important?
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Catabolic pathways release energy by breaking down complex molecules into simpler
compounds
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Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a
pathway of catabolism
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Kinetic energy is energy associated with motion
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Heat (thermal energy) is kinetic energy associated with random movement of atoms or
molecules
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Potential energy is energy that matter possesses because of its location or structure
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Chemical energy is potential energy available for release in a chemical reaction
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Energy can be converted from one form to another
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Every energy transfer or transformation increases the entropy (disorder) of the universe
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The evolution of more complex organisms does not violate the second law of thermodynamics
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Entropy (disorder) may decrease in an organism, but the universe’s total entropy increases
ATP powers cellular work by coupling exergonic reactions to endergonic reactions
CHAPTER 10 STUDY GUIDE
Key Concept: The Process That Feeds the Biosphere: PHOTOSYNTHESIS
What are Autotrophs?
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Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes
These organisms feed not only themselves but also most of the living world
Concept 10.1: Photosynthesis converts light energy to the chemical energy of food
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Chloroplasts are structurally similar to and likely evolved from photosynthetic bacteria
The structural organization of these cells allows for the chemical reactions of photosynthesis
What are Stomata, thylakoids, stroma?
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Photosynthesis is a complex series of reactions that can be summarized as the following
equation: 6 CO2 + 12 H2O + Light energy  C6H12O6 + 6 O2 + 6 H2O
Concept 10.2: The light reactions convert solar energy to the chemical energy of ATP and NADPH
Photosynthetic Pigments: The Light Receptors
• Pigments are substances that absorb visible light
• Different pigments absorb different wavelengths
• Wavelengths that are not absorbed are reflected or transmitted
• Leaves appear green because chlorophyll reflects and transmits green light
Concept 10.4: Alternative mechanisms of carbon fixation have evolved in hot, arid climates
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Dehydration is a problem for plants, sometimes requiring trade-offs with other metabolic
processes, especially photosynthesis
On hot, dry days, plants close stomata, which conserves H2O but also limits photosynthesis
The closing of stomata reduces access to CO2 and causes O2 to build up
These conditions favor an apparently wasteful process called photorespiration
Photorespiration may be an evolutionary relic because rubisco first evolved at a time when the
atmosphere had far less O2 and more CO2
Photorespiration limits damaging products of light reactions that build up in the absence of the
Calvin cycle
In many plants, photorespiration is a problem because on a hot, dry day it can drain as much as
50% of the carbon fixed by the Calvin cycle
In the last 150 years since the Industrial Revolution, CO2 levels have risen greatly
Increasing levels of CO2 may affect C3 and C4 plants differently, perhaps changing the relative
abundance of these species
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The effects of such changes are unpredictable and a cause for concern
Big Picture Questions: Relate what you have learned to the world around you. 1. Why is
photosynthesis important from an environmental standpoint?
2. Do the above facts relate to global climate change?
3. Will less photosynthesis occurring have a negative impact on humanity?
4. What do you think can be done to address this?
Chapter 22
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Evolution can be defined by Darwin’s phrase descent with modification
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Understand the history of the natural sciences
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Why was Darwin’s idea considered dangerous?
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The study of fossils helped to lay the groundwork for Darwin’s ideas
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Fossils are remains or traces of organisms from the past, usually found in sedimentary rock,
which appears in layers or strata
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Notable people: Lyell, Hutton, Cuvier, Malthus, Lamarck
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Uniformatarianism
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Adaptation
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Population
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Role of Darwin’s Finches
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Tree of Life concept (phylogenetic tree)
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Darwin then described four observations of nature and from these drew two inferences
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Observation #1: Members of a population often vary greatly in their traits
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Observation #2: Traits are inherited from parents to offspring
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Observation #3: All species are capable of producing more offspring than the environment can
support
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Observation #4: Owing to lack of food or other resources, many of these offspring do not survive
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Inference #1: Individuals whose inherited traits give them a higher probability of surviving and
reproducing in a given environment tend to leave more offspring than other individuals
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"The higher chances of survival, the more offspring they have"
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example: fishes, frogs, birds, insects
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Inference #2: This unequal ability of individuals to survive and reproduce will lead to the
accumulation of favorable traits in the population over generations
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"Those that survive will bring the favorable traits with them"
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Note that individuals do not evolve; populations evolve over time
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Natural selection can only increase or decrease heritable traits in a population
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Adaptations vary with different environments
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Homology evidence (forelimb)
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Pakicetus, etc.
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Vestigial structures
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Covergent Evolution
Chapter 23
Micro evolution
Macroevolution
Evolution of populations
Point mutations
Variation through mutation and sexual reproduction
Population genetics
Heterozygosity
Mutations
Populations
Gene pool
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The Hardy-Weinberg principle states that frequencies of alleles and genotypes in a population
remain constant from generation to generation
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In a given population where gametes contribute to the next generation randomly, allele
frequencies will not change
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Mendelian inheritance preserves genetic variation in a population
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Hardy-Weinberg equilibrium describes the constant frequency of alleles in such a gene pool
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If p and q represent the relative frequencies of the only two possible alleles in a population at a
particular locus, then
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p2 + 2pq + q2 = 1
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where p2 and q2 represent the frequencies of the homozygous genotypes and 2pq
represents the frequency of the heterozygous genotype
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The Hardy-Weinberg theorem describes a hypothetical population, not always occurs in nature
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In real populations, allele and genotype frequencies do change over time
Genetic drift
Founder effect – blue Fugates
Bottle neck effect
Gene flow
Fitness? Evolutionary sense
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Three modes of selection:
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Directional selection favors individuals at one end of the phenotypic range
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Disruptive selection favors individuals at both extremes of the phenotypic range
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Stabilizing selection favors intermediate variants and acts against extreme phenotypes
Sexual selection
Sexual dimorphism
Intrasexual selection
Intersexual selection
Why Natural Selection Cannot Fashion Perfect Organisms
1. Selection can act only on existing variations, favors the fittest
2. Evolution is limited by historical constraints, does not "occur" out of the blue
3. Adaptations are often compromises
4. Chance, natural selection, and the environment interact