SCS Final
Biology
Caleb Phillips
SCS 110
In-Class Notes
Topic: Energy Use in Biological Systems Continued
I. Body energy balance for humans
1. Food as fuel
· Fiber is a carb, but not broken down by the body
- Fuel values to memorize:
o Carbohydrates – 4 kcal/g
o Fats and oils – 9 kcal/g
o Proteins – 4 kcal/g
o Non-digestible fiber – 0
o Water – 0
2. Food Calories
A. Food labels list calories
B. A food calorie is equal to a kilocalorie or fuel value
- The calculation to find calories amount for things like fat and carbs has to do with multiplying the grams of x by the kcal/g value for that thing, yielding kcal, what we consider to be calories
3. Body Energy Balance Equation
I = R + S/G
- energy intake = (heat + biological work) + storage/growth
- intake = Respiration + Storage/Growth
o R is also called the metabolic rate
4. Metabolic Rate, R
· Affected by activities (some require more energy than others)
o For example: the metabolic rate (kcal/hour) while lying quietly awake is 77; sitting at rest, 100; typing at a computer, 140; shoveling snow, 480; jogging at 5.3 mph, 570; (swimming 625 kcal/hour).
§ The metabolic rate is the rate at which our body uses energy.
· The amount of energy needed to maintain basic bodily functions is called the basal metabolic rate or BMR.
· BMR varies across individuals due to things like body size, age, sex, stress level, genetics. Average for 154-pound adult is 1440-1728 kcal per day.
· BMR can be determined by measuring the heat given off by a person or by measuring the amount of Oxygen they use (for cellular respiration).
o There are ways to determine a person’s BMR with a calorimetry chamber. It can be difficult to do this accurately. Another way to measure this is the 3rd point, Oxygen use.
5. Gain and loss of weight
Equation (I = R +S/G) demonstrates conservation of energy
Can rearrange to: S/G = I – R
· Weight gain:
o If (I) is greater than R, S/G is positive, and the body will use extra energy to store fat or grow protein
o For positive S/G, there is a need to increase I or decrease R
§ Helpful conversion: 1lb = 454g
· Weight loss
o If (I) is less than R, S/G is negative, and the body will use stored fat or muscle for energy.
o For negative S/G, there is a need to decrease I or increase R
§ The body will decrease its BMR if starved, it will increase its BMR if exercise.
6. Sample problem
· How long will it take someone whose average metabolic rate is 2800 kcal/day to lose 25 pounds of fat if he goes on a 2000 kcal/day diet?
II. Temperature regulation
1. Ectotherms – creatures whose body temperature is not internally regulated and therefore will take the temperature of their environment (cold-blooded) (reptiles, fish, insects, and all other invertebrates).
· a snake may hide in the shade to stay cool
· a lizard may fight of sickness by going closer to heat lamp
- They don’t need to make as much heath, so they don’t need as much food or O2 for cellular respiration.
2. Endotherms – creatures whose body temperature IS internally regulated and therefore will maintain a constant body temperature independent of their environment. (98.6 degrees F is 37 degrees C for humans)
· Mammals and birds
· Extra cellular respiration for warmth. Need more food and O2 (more complex lungs).
· We need more food because we need to keep our internal temperature up (as compared to a fish or ectotherm)
3. Hibernation
A. A strategy of some mammals to survive long winter months with scarce food.
o Groundhogs, chipmunks
o Black bears are semi-hibernators or maybe just deep sleepers
B. Basal metabolic rate drops so that stored body fat provides enough energy for several months.
I = R + S/G
I = 0
R = -S/G
Body temperature drops, cell activity slows down
Caleb Phillips
SCS 110
In-Class Notes
Topic: Photosynthesis
Animals feed on other organisms to get fuel for cellular respiration. Plants make their own fuel by a process called photosynthesis.
I. What is the source of plant biomass?
1. Aristotle said that plants have roots in the soil, so the soil must provide biomass.
2. Nicholas of Cusa in 1450 suggested that it comes from water, no soil. This was his hypothesis. He proposed an experiment, but never did it. The experiment was to carefully weigh the soil, grow a plant in it, then weigh the soil again. The weight of the soil should not change.
3. Jan Baptiste van Helmont, in the 1640s, performed the experiment to test Cusa’s hypothesis. His conclusion was that the soil was nearly the same before and after, but the mass of the tree was much different. He concluded that water only was responsible. This doesn’t prove that it comes from the water but only does not come from the soil.
4. Steven Hales (1717) proposed that air provided nourishment. No experiments, though. He thought that plants absorbed air through leaves (not roots) and converted a part of the air into solid material.
· Hales did do some work in physics and chemistry but he work a lot in biology and botany also. Had the view that God upholds the laws of the universe. He was an Anglican clergyman too.
5. Joseph Priestly (discovered O2) found that “fixed air” results from burning a candle in a closed chamber (O2 consumed, CO2 produced). Plants could restore the air (reverse the action of the flame) (CO2 consumed, O2 produced).
· He had inconsistent results though. It didn’t work in the night, but it did work in the day.
6. In 1779, Austrian physician Jean Ingen-Housz demonstrated that the inconsistent results were caused by changes in light intensity. Sunlight is required for photosynthesis.
7. Photosynthesis: overall reaction
· Green plants with light:
o 6CO2 + 6H2O Yields C6H12O6 + 6O2
§ Carbon dioxide plus water yields glucose and oxygen
8. Photosynthesis is complex (just like respiration):
· Light reactions – use light energy to make high-energy molecules
· Dark reactions: use energy from the high-energy
II. Details of Photosynthesis
1. Happens in the green parts of plants. “chloro” means green
A. Chloroplast: cell organelle where photosynthesis happens
B. Chlorophylls are the molecules that absorb light. They absorb blue and red light, so they look green.
C. Chlorophylls absorb light at 400-490 nm and 610-680 nm.
o Depending on if the molecule is chlorophyll a or b, the range is slightly different but roughly the same.
· The peak of the sun’s emission is around 510 nm, so it is a great light source for photosynthesis.
D. The first step in photosynthesis is light absorption. What happens? Electron jumps to a higher energy level.
2. Light reactions
A. Chlorophyll absorbs light, an electron is excited to a higher energy level.
B. The high-energy electron is unstable and transfers to make either ATP or NADPH (high-energy molecules)
C. Chlorophyll gets a replacement for its lost electron from water
o H2O + 2 energized chlorophyll (+) yields 2 H (+) + ½ O2 + 2 chlorophyll
D. The plant is trying to make a fuel for energy. Here it has made ATP. Why not stop here? Why continue to make glucose?
o The plant needs energy all over the plant. The ATP cannot be stored or transferred; it is unstable. Light reactions can only provide ATP to green cells while the sun is shining, but all plant cells need ATP all the time. The dark reactions are thus necessary to make glucose, a fuel that can only be stored and transported, then used for cellular respiration to make ATP where and when it is needed.
3. Dark reactions
· Also known as the Calvin cycle. Named after Melvin Calvin (1911-1997)
A. These occur after the light reactions.
B. “Dark” means the reactions don’t directly use light. They still mostly happen during the day because they need the ATP and NADPH from the light reactions.
C. Overview of the dark reactions
o PGA and PGAL are 3-carbon molecules. High energy ATP and NADPH are used as sources of chemical energy in this process.
§ The 2 PGALs will be used to yield glucose
4. Summary of the photosynthesis equation
6CO2 + 6H2O [yield (light)] C6H12O6 + 6O2
- CO2 is used in the dark reactions and H2O is used in the light reactions, Glucose is produced in the dark reactions, O2 in the light.
- Glucose can be stored, transported, used as fuel for respiration, or converted into other materials like starches, fats, and proteins.
o Plants use sap to transport sugars; it is like their “blood.”
III. The big picture for an ecosystem
1. Consider energy relationships in communities of plants (ecological perspective).
2. Terms:
o Gross Primary Production (GPP): total amount of glucose chemical energy produced in entire plant community.
o Respiration (R): Energy needed to keep the plants alive.
o Net Primary Production (NPP): leftover energy used for storage and growth.
3. Overall scheme of Radiant energy to growth or heat
o (Shown via diagram in class).
§ NPP = plant growth = biomass = chemical energy
§ GPP = R +NPP
Caleb Phillips
SCS 110
In-Class Notes
Topic: Photosynthesis pt. 2
Overview of GPP=R+NPP
· GPP, or gross primary production, is the rate at which the plant community is making chemical energy in the form of glucose.
· NPP, or net primary production, goes into plant growth
· R, respiration, is for cellular respiration (ATP) to continue biological work to keep the plant alive
· Heat
o The values of each depend on the community of plants, things like lake phytoplankton, a forest, a meadow, and more.
I. Limiting Factors
Limits on photosynthesis (GPP) will limit plant growth (NPP)
1. Sunlight
A. Only about 2% of solar energy is captured by photosynthesis
B. In PA, our sunlight is limited
- Where you are leads to differences in amount of sunlight that gets through to plants
2. Water
o You need water to do photosynthesis. You use CO2 and H2O in the equation. In general, there is a positive correlation between rainfall and net primary production. Plants can also lose water though; there are little holes called (stoma) (I think) that control water retention
3. Mineral Nutrients
A. ATP contains N and P.
B. Green plants use potassium (K).
C. Chlorophyll contains Mg.
D. Plants also need Ca, Fe, and other minerals.
E. Fertilizer in the ocean comes from dead fish
· Carnivorous plants use bugs as fertilizer
Caleb Phillips
SCS 110
In-Class Notes
Topic: Food Chains (Ch. 19)
I. Overview of Energy Flow in Ecosystems
1. Net Primary Production by plants
- Starts with the Sun
- GPP
2. NPP represents stems, trunks, leaves, seeds, and flowers
3. Consumers obtain fuel for cellular respiration from plants and other animals. Consumers don’t produce their own food, glucose. Anything that is feeding on something else. (how about a Venus fly trap?)
II. Primary Consumers in an Ecosystem
1. Animals that eat plants are called herbivores, also known as primary consumers
2. Herbivores eat some of the NPP but not all of it.
- The primary consumers eat some of the primary production, some in not ingested.
3. Some of what is eaten is digested and assimilated.
o The rest is excreted as feces.
o The percentage of ingested energy that is assimilated is the assimilation efficiency
4. Assimilation efficiency:
Assimilation eff. = food energy assimilated/food energy ingested = A/I (*100)
- There are differences in assimilation efficiency based on the consumer.
o E.g. A meadow mouse has about a 70% AE (herbivore)
o A horse, 56% (it is a non-ruminant)
o A weasel is a carnivore, its eff. Is 96%
o A sheep is a ruminant has 59%
§ Why is this?
§ Fiber is not absorbed by bodies very well, so it is excreted.
§ The carnivore, weasel, eats a diet that has protein and fats. These things are more digestible.
· Ruminants have a special stomach to digest plants
5. Energy relationships for a primary consumer
o Of the NPP, some is ingested, some not; some is assimilated (C1P), some excreted as feces; some is used for primary consumer production, some for respiration—and heat.
§ NPP = I + NI (ingested, not ingested)
§ I = A + F
§ A = R + CP
· CP or C1P
§ Growth efficiency = consumer production/ingested food energy = CP/I
- The amount of NPP depends on the region. The Amazon visibly has much more than the Sahara.
III. Examples
1. Savannah ecosystem
o NPP = 758 kcal m^2/yr
Caleb Phillips
SCS 110
In-Class Notes
Topic: Food Chains (Ch. 19) pt. 2
Assimilation efficiency = A/I = (I-F)/I
Growth efficiency = (CP)/I
2. A typical meadow / border-woodland ecosystem
A. NPP = 4954 kcal/m^2/yr
a. This is much larger than the savannah
- Many plant species
- Many primary consumer species (including insects)
- Many secondary consumer species (i.e. predators)
B. The primary consumer production is the amount of energy that is available to the next level of the food chain.
o Food chain efficiency shows how much energy is moving forward through the links of the chain. The production at a level divided by the production at a previous level, C1P / NPP OR C2P / C1P OR C3P / C2P …
§ For weasels feeding on mice, we would consider the equation, C2P / C1P, then we would find C2P, which is the A – R, so that would be 0.109 – 0.102 = 0.007. we are given C1P.
· 0.007 kcal/m2/year divided by 0.60 kcal/m2/year which is 0.012 = 1.2%
- This shows that the higher the level of CP, the less energy available. This shows that there can only be so many high-level consumers. Is this problematic for us as people? It certainly doesn’t make things better for us, but we do eat plants and animals.
3. What about the leftover chemical energy in an ecosystem?
A. NI and F from all levels are collectively called “detritus” dead plants, animal carcasses, feces, etc.
§ NI means not ingested, F is Feces
· These things still have chemical energy
B. Detritus still contains chemical energy that could be used as fuel by some organisms.
- Decomposition: the process of extracting energy from detritus. Could be done by bacteria or other organisms
- Dead plant material is eaten by detritivores (e.g. earthworms).
o Any remaining fragments, as well as detritive feces, are broken down by decomposers like bacteria and molds in the soil.
- Bacteria and molds might be eaten by other organisms.
o even a handful of dirt is more intricate than it seems
C. Some detritivores and decomposers feed on dead animal material and feces. The decomposition of material in soil provides fertilizer for plants.
Caleb Phillips
SCS 110
In-Class Notes
Topic: Finishing Ch. 19 – Food Chains
I. Humans in the Food Chain
1. Humans are consumers.
A. We are typically neither all herbivores nor carnivores.
B. We could be primary or secondary consumers.
- If a person is eating plant products, they are functioning as a primary consumer.
- If a person is eating animal products, they are functioning as a secondary consumer.
2. Available energy and carrying capacity – the amount of energy at one level is not available to the next because of how that energy is used. Not all of the energy is used to continue in the food chain.
§ Let the blue area be energy (E)
A. The population level that can be supported by the resources (particularly the NPP) of an area is that area’s carrying capacity.
B. An area can support more herbivores than carnivores.
§ How should we as humans respond to this? We could feed more people if we only ate plants, in theory.
3. So, should we eat plants exclusively?
o If everyone became vegetarians, food insecurity would remain.
A. Economics: some can’t afford any kind of food
B. Reducing meat consumption does not equal more plant food.
C. Land for livestock is not always suitable for ag-plants.
D. Good roads and food storage can be limited.
4. Meat consumption is high in many countries; higher than our bodies need.
o The average protein requirement for a 150-pound person is about 60 grams a day. This varies greatly for the type of person: an athlete, a child-bearing mother, etc.
§ There are countries that are above and below the average requirement for protein.
5. Food chain metrics
For every certain amount of animal products and plant product that we eat, what amount of energy was needed to get those products to us?
o There are many factors in both animal and plant products, more in animal products, animal products take more E to develop and distribute.
You can break this down more:
o NPP is first
o This gets broken down into crop residue, exports, non-food
o Consider—machinery, grain drying, irrigation, field operation, other petroleum use, fertilizer and pesticide, total fossil fuel used.
o Domestic food and feed: some goes to animals, some goes to plant food for humans. Food scraps to animals.
§ To animal feed is manure, respiration in farm animals, waste and by-products. Form animal feed is energy in animal products and from plants, energy in pant products. There is more E in plant products than animal products.
· More food can be made available if more plant products given to people rather than animals.
6. Animal products are healthy for us though. We need specific amino acids to perform cellular functions. For example, genetic defects come from amino acid issues. There are altogether 20 amino acids. There are 8 that are essential.
o Meat and eggs have a good balance of the amino acids.
o Dairy products can be short; most plant protein sources are short if eaten on their own.
§ You can get the amino acids you need with plant and dairy products but one must be mindful.
7. Combination of various foods can supply protein.
the concept of complementary proteins – food sources that contain amino acids that match the human protein needs.
- Meats and eggs are already complete
- Grain and legume
- Grain and dairy
8. Animal products are also a good source of micronutrients.
o Some vitamins and minerals are found in animal products in higher quantities than in plant products.
o Some nutrients are found in animal products in forms that are easier for the body to absorb.
o A person eating a began diet will be at higher risk of nutritional deficiencies and will need to be mindful of this.
9. Fossil fuels and food
- First consider the fossil fuel inputs. To grow, transport, and cook.
o Some ways to be better stewards of food and the energy required to obtain it:
§ Support sustainable farming practices
§ Buy locally produced food when possible
§ Reduce food waste.
§ Use the whole animal
10. Consider food waste
o 30-40% of food in America is thrown away
§ 5 units of food energy requires 55 units of NPP, 35 units of fossil fuels
Caleb Phillips
SCS 110
In-Class Notes
Topic: Ch. 20 | Retrospection on the Natural World and the Scientific Endeavor
I. Key underlying assumption for studying natural processes
1. The natural world is God’s creation.
2. God constantly rules His creation in a providential way.
3. Science is the study of God’s orderly creation.
4. Science is a human process shaped by its practitioners.
· These may not affect how you do science, but they do affect how you view science.
II. Principles of science
1. Science is a human process shaped by culture and influenced by the fallibility and sinfulness of humans.
2. Scientific theories are dependent on data.
3. Scientific data and ideas are analyzed quantitatively. There are some qualitative aspects though.
4. Controlled experiments occupy a central role in the process of science.
§ Galileo’s inclined planes
§ Rutherford’s gold foil
§ Etc.
5. Science distinguishes facts from hypotheses and theories from opinions.
6. Scientific ideas develop over time.
§ Sometimes new technology is needed
7. Science and the scientific method are limited. Theories are not absolute truth statements. It can’t answer questions or morality, ethics, or policy.
8. Science provides necessary information and tools for effective stewardship of creation.
- Science can’t tell us that we should be good stewards or why. But it can give us information that can help us understand how to be good stewards of creation.
o How can we be better stewards of the blessings of creation?
Caleb Phillips
SCS 110
In-Class Notes
Topic: Last Class
Top 15 Scientists
· Aristotle
· Ptolemy
· Copernicus
· Kepler
· Galileo
· Newton
· Joule
· Maxwell
· Priestley
· Lavoisier
· Mendeleev
· Dalton
· Thomson
· Rutherford
· Van Helmont
- Know the rough time-period and their important contributions
Caleb Phillips
SCS 110
Additional Notes
Topic: Ch. 16 | Muscles
I. Energy in living creatures: a move from chemistry to biology
1. Glucose is a fuel for our bodies
2. Energy is used by our bodies even when we are sleeping.
· Heart pumping blood
· Digestive system
· Replacing old cells
· Heat to maintain body temp
· Using muscles to move around
· Etc.
3. Three general types of biological work
A. Muscle contraction: voluntary or involuntary
B. Active transport: moving molecules across membranes
C. Molecular synthesis: making new molecules, tissues, etc.
II. Muscles structure
1. Large skeletal muscles: easier to explore.
A. Belly of the muscle: thick section in the middle.
o Muscles only exert force when they contract
o Muscles are arranged in opposition so force can be exerted in the other direction.
2. Muscle fibers
A. Muscles are made up of bundles
B. The bundles are made up of long, cylindrical cells called muscle fibers
C. Muscle fibers are large cells, much larger than other cells
3. Myofibrils
A. Muscle fibers are made up of smaller fibers called myofibrils
B. Myofibrils are perfectly aligned to make muscles looked striped
C. Myofibrils contain dark lines, Z-lines
4. Proteins of the myofibrils
A. Myofibrils contain myofilaments, there are thin and thick filaments
B. Actin is the thin, myosin is the thick.
Caleb Phillips
SCS 110
Additional Notes
Topic: Ch. 17 | Energy Use in Biological Systems
I. Biological work – energy usage in living creatures.
A. Muscle contraction
B. Active transport
C. Etc.
o Cells get the energy needed for these processes from a molecule, the source of chemical energy, ATP
ATP is like an energy shot for the cell. Adenosine triphosphate.
The bonds are called “high energy” bonds
· The negative charges repel each other, so it takes energy input to bring them closer together.
· Due to the negative charge being held in proximity, ATP has a high chemical potential energy.
· Energy is released when a ~ bond is broken, and one phosphate is allowed to move away from the others.
ATP reacts with water to break a negative ~ bond and form ADP and Pi. This reaction has a delta HR of -73 kcal/mol
Because ATP is so unstable, it cannot be stored or transported, the cell must make it.
· The production of ATP is called cellular respiration and happens in or near the mitochondria.
II. Production of ATP – cellular respiration
Cellular respiration is the process of breaking down food molecules to release chemical energy.
· Respiration is a complex process
· Oxygen is used
1. Glycolysis: breaking down glucose in the cytoplasm.
A. It is quick, anerobic energy: can make some ATP without O2.
B. 10 reactions from glucose to pyruvic acid.
2. Krebs cycle (or the citric acid cycle)
A. Cyclic series of reactions in the mitochondria overall
B. Pyruvate is stripped of additional H to form NADH, another high energy molecule
C. CO2 is also produced
D. Combustion of 2 pyruvic acids
3. The electron transfer chain
4. The importance of O2
A. Without O2, the process comes to a halt
B. Red blood cells carry O2
Previous Topics/Misc
COMPREHENSIVE STUDY GUIDE (FILLED IN)
1. HISTORY OF SCIENCE & SCIENTIFIC METHOD
Scientific Method (Core Ideas)
Observation → Hypothesis → Experiment → Data → Conclusion
Must be:
Empirical (based on evidence)
Repeatable
Testable/Falsifiable
Christian perspective: studying creation reveals order and consistency, reflecting a rational Creator
a. Galileo vs. Philosophy
Aristotle: relied on logic and speculation
Galileo: used controlled experiments and measurement
Key shift: science moved from philosophy to experimentation
b. Experiments that Disproved Old Ideas
Galileo (Falling Objects)
Aristotle: heavier objects fall faster
Galileo: all objects fall at the same rate (ignoring air resistance)
Lavoisier (Phlogiston Theory)
Old idea: substances release “phlogiston” when burned
Lavoisier: combustion involves oxygen
Led to the Law of Conservation of Mass
Rutherford (Atomic Model)
Thomson: “plum pudding” model
Rutherford: dense nucleus (gold foil experiment)
van Helmont (Plant Growth)
Thought plants gained mass from soil
Found mass mainly comes from water (later understood as CO₂ as well)
c. Empirical Laws → Theories
Kepler’s 3rd Law → explained by Newton’s Law of Gravity
Balmer equation → explained by Bohr model
Mendeleev’s periodic table → explained by electron shell theory
Key idea: observations come first, explanations follow
2–3. ENERGY TYPES & EQUATIONS
Kinetic Energy
KE=12mv2KE=21mv2
Energy of motion; depends on mass and velocity squared
Gravitational Potential Energy
PEg=mghPEg=mgh
Stored energy due to height
Other Energy Types
Heat (thermal):
Lowest-quality energy
Always produced
Cannot be converted at 100% efficiency
Electrical Energy:
EE=VItEE=VIt
Very versatile
Difficult to store in large quantities
Radiant Energy (light):
Spectrum from radio waves to gamma rays
Sun is the primary energy source on Earth
Chemical Energy:
Stored in chemical bonds
Found in food, fuels, and batteries
Energy Conversions
Falling → kinetic energy
Battery → electrical energy
Light → chemical energy (photosynthesis)
Chemical → mechanical (muscles)
4. CONSERVATION OF ENERGY
Energy cannot be created or destroyed
Only transformed from one form to another
Total energy remains constant
Some energy is always lost as heat
5. ELECTRICITY GENERATION (POWER PLANT)
Steps:
Fuel is burned to produce heat
Heat turns water into steam
Steam spins a turbine
Turbine drives a generator to produce electricity
Major losses:
Heat lost during combustion
Heat lost in steam transfer
Friction in machinery
Waste heat released to environment
6. PETROLEUM BENEFITS
High energy density
Easy to transport
Relatively stable and safe
Efficient for engines
BIOLOGY UNIT
Chapter 16 – MUSCLE CELLS
Types of Biological Work
Mechanical (movement)
Transport (across membranes)
Chemical (building molecules)
Muscle Structure
Muscle fiber → myofibrils → sarcomeres
Sarcomeres contain:
Actin (thin filaments)
Myosin (thick filaments)
Z-lines mark boundaries
Muscle Contraction
Myosin pulls actin → sarcomere shortens
Requires ATP
Chapter 17 – ATP & CELLULAR RESPIRATION
ATP
Main energy-transfer molecule
Stores energy in phosphate bonds
Powers cellular work
Cellular Respiration (3 Steps)
Glycolysis (cytoplasm)
Krebs Cycle (mitochondria)
Electron Transport Chain
Overall Reaction
C6H12O6+6O2→6CO2+6H2O+ATPC6H12O6+6O2→6CO2+6H2O+ATP
Requires oxygen
Produces about 30–32 ATP
Efficiency around 30–40%
Fuel Values
Carbohydrates: 4 kcal/g
Proteins: 4 kcal/g
Fats: 9 kcal/g
Water and fiber: 0
Basal Metabolic Rate (BMR)
Energy used by the body at rest
Thermoregulation
Endotherms: regulate internal temperature
Ectotherms: rely on environment
Hibernators: reduced metabolism
Chapter 18 – PHOTOSYNTHESIS
Source of Plant Biomass
Comes primarily from CO₂ and water, not soil
Overall Reaction
6CO2+6H2O+light→C6H12O6+6O26CO2+6H2O+light→C6H12O6+6O2
Light Absorption
Chlorophyll absorbs light
Converts radiant energy into chemical energy
Two Stages
Light reactions: produce ATP and NADPH
Dark reactions (Calvin Cycle): produce glucose
ATP vs Glucose
ATP is short-term energy
Glucose is long-term storage
GPP and NPP
GPP: total energy captured
NPP: energy after respiration
NPP = GPP − R
Limiting Factors
Light intensity
Water availability
Nutrients (N, P, K, Mg)
Mature vs Young Ecosystems
Mature forests: high respiration → lower NPP/GPP
Young plants: rapid growth → higher NPP
Chapter 19 – ECOLOGY & ENERGY FLOW
Energy Flow
GPP → NPP → consumers
Energy lost as heat at each level
Efficiencies
Assimilation efficiency: absorbed vs ingested
Growth efficiency: growth vs absorbed
Trends
Carnivores: higher assimilation efficiency
Herbivores: lower
Ectotherms: higher growth efficiency than endotherms
Food Chain Levels
Primary producers (plants)
Primary consumers (herbivores)
Secondary consumers (carnivores)
Detritus
Dead organic matter
Used by decomposers
Energy Costs of Food
Plants: ~2:1 energy input
Meat: ~25:1
Fossil fuels: ~7:1
Carrying Capacity
Maximum population an environment can support
Protein
Found in meat, beans, nuts
Needed for growth, repair, enzymes
Food Waste
Wasting food wastes energy from:
Sunlight
Plants
Animals
Fossil fuels
EQUATIONS TO KNOW
d = vt
W = Fd
KE = ½mv²
PE = mgh
Q = mcΔT
EE = VIt
P = VI
1 cal = 4.18 J
1 kWh = 3.6 × 10⁶ J
PRACTICE MULTIPLE CHOICE (Q → A FORMAT)
1. Which of the following is not a form of biological work?
Answer: B. storage of excess food energy
2. Cellular respiration takes place in structures within the cell that are called...
Answer: B. mitochondria
3. Rusty drives across Pennsylvania at 55 miles per hour for 4 hours. How far does he go?
Answer: C. 220 miles
4. If 120 V is applied to a 60 ohm resistor, what is the current across the resistor?
Answer: C. 2.0 A
5. An engine operates between 800°C and 90°C. What is the efficiency?
Answer: A. 0.66
6. If you spend $150 at a rate of $0.08/kWh, how many kWh were used?
Answer: A. 1875 kWh
7. Why does a mammal consume more energy than a lizard at the same temperature?
Answer: C. the mammal needs to produce more heat
8. Which of the following is true of ATP?
Answer: C. It has to be produced in the cell where it will be used
9. What is the formula mass of pentane given the data?
Answer: A. 72.0 g/mol
10. What is the kinetic energy of a 10 kg bowling ball rolling at 6 m/s?
Answer: C. 180 joules
11. How much work is done when a force of 18 N moves an object 200 cm?
Answer: B. 36 joules
12. What is the increase in potential energy of a 9 kg object lifted 15 m?
Answer: D. 1323 joules
13. If growth efficiency is 72% and ingestion is 0.125 kcal/m²/yr, what is growth?
Answer: B. 0.09
14. If mice ingest 28 kcal/m²/yr and feces is 7.6 kcal/m²/yr, what is assimilated?
Answer: D. 20.4
15. If ingestion is 0.125 and assimilation is 0.120, what is assimilation efficiency?
Answer: A. 96%
16. If GPP = 6500 and NPP = 5200, what is respiration?
Answer: B. 1300
17. If intake is greater than metabolic rate, what happens?
Answer: A. He will gain weight at a rate of 0.073 pounds per day
18. If 1 glucose produces 38 ATP, how many glucose molecules produce 9500 ATP?
Answer: C. 250 molecules
ADDITIONAL BIOLOGY PROBLEMS (Q → A WITH EXPLANATIONS)
1. A one-half cup serving of ice cream contains 39 g water, 17 g carbohydrate, 8 g fat, and 2 g protein. How many kilocalories does it contain?
Answer: 148 kcal
Explanation:
Only macronutrients contribute energy:
Carbohydrates = 4 kcal/g → 17 × 4 = 68 kcal
Fat = 9 kcal/g → 8 × 9 = 72 kcal
Protein = 4 kcal/g → 2 × 4 = 8 kcal
Water = 0 kcal
Total = 68 + 72 + 8 = 148 kcal
2. Jeff has a metabolic rate of 2500 kcal/day but consumes 2000 kcal/day. What is his weight change after 30 days?
Answer: Loss of 3.7 pounds
Explanation:
Daily deficit = 2500 − 2000 = 500 kcal/day
Over 30 days: 500 × 30 = 15,000 kcal
Convert to pounds:
1 lb ≈ 4000 kcal
15,000 ÷ 4000 = 3.7 lbs lost
3. A forest has total photosynthesis of 83,000,000 kcal/yr and biomass increase of 24,000,000 kcal/yr. What are GPP, NPP, and R?
Answer:
GPP = 83,000,000 kcal/yr
NPP = 24,000,000 kcal/yr
R = 59,000,000 kcal/yr
Explanation:
Use the relationship:
GPP = NPP + R
Solve for respiration:
R = GPP − NPP
R = 83,000,000 − 24,000,000 = 59,000,000
4. Fish eat insects at 0.55 kcal/m²/yr with 72% assimilation efficiency and growth of 0.15 kcal/m²/yr. What are A, F, R, and growth efficiency?
Answer:
A = 0.40 kcal/m²/yr
F = 0.15 kcal/m²/yr
R = 0.25 kcal/m²/yr
Growth efficiency = 27%
Explanation:
Step 1: Assimilation
A = assimilation efficiency × ingestion
A = 0.72 × 0.55 ≈ 0.40
Step 2: Feces
F = I − A = 0.55 − 0.40 = 0.15
Step 3: Respiration
R = A − growth = 0.40 − 0.15 = 0.25
Step 4: Growth efficiency
growth / ingestion = 0.15 / 0.55 ≈ 27%
5. Rabbits consume 9200 kcal, excrete 3200 kcal, and gain 400 kcal. What are A, R, assimilation efficiency, and growth efficiency?
Answer:
A = 6000 kcal
R = 5600 kcal
Assimilation efficiency = 65%
Growth efficiency = 4.3%
Explanation:
Step 1: Assimilation
A = I − F = 9200 − 3200 = 6000
Step 2: Respiration
R = A − growth = 6000 − 400 = 5600
Step 3: Assimilation efficiency
A / I = 6000 / 9200 ≈ 65%
Step 4: Growth efficiency
growth / I = 400 / 9200 ≈ 4.3%
SCS 110 REVIEW QUESTIONS (Q → A WITH EXPLANATIONS)
2. Describe the series of energy transformations when a person eats bread and then runs up a mountain.
Answer:
Chemical energy (bread) → chemical energy (glucose) → ATP → mechanical energy (muscles) → kinetic energy (movement) → heat
Explanation:
Bread contains chemical energy stored in carbohydrates
Digestion converts it to glucose
Cellular respiration converts glucose into ATP
ATP powers muscle contraction
Muscles produce movement (kinetic energy)
A large portion of energy is lost as heat
3. Describe the role of ATP in muscle contraction and how sarcomeres shorten.
Answer:
ATP provides the energy for myosin heads to attach, pull, and release actin, causing sarcomeres to shorten.
Explanation:
ATP binds to myosin → allows detachment from actin
ATP is hydrolyzed → energizes myosin head
Myosin pulls actin inward (power stroke)
Repeated cycles shorten the sarcomere
This is called the sliding filament theory
4. Describe the key experiments that led to the modern theory of photosynthesis.
Answer:
Key scientists showed that plant mass comes from water and CO₂, and that light is required for oxygen production and energy conversion.
Explanation:
van Helmont: plants gain mass mainly from water
Priestley: plants restore oxygen to air
Ingenhousz: light is required for oxygen production
Result: photosynthesis uses light + CO₂ + water → glucose + O₂
5. Compare the roles of light reactions, dark reactions, and cellular respiration in a tomato plant.
Answer:
Light reactions: capture light energy → produce ATP and NADPH
Dark reactions: use ATP to make glucose
Cellular respiration: breaks glucose to make ATP for the plant
Explanation:
Light reactions store energy temporarily
Dark reactions store energy long-term (glucose)
Respiration allows cells to actually use that energy
6. Describe energy flow from grasses → mice → weasels. Why does little energy reach weasels?
Answer:
Energy flows from plants to herbivores to carnivores, but most is lost as heat at each step.
Explanation:
Grass captures solar energy → chemical energy
Mice eat grass → lose energy through metabolism and heat
Weasels eat mice → even more energy lost
Only about 10% transfers to the next level
Therefore, very little energy reaches top predators
7. How does human diet affect Earth’s carrying capacity?
Answer:
Plant-based diets increase carrying capacity, while meat-heavy diets decrease it.
Explanation:
Producing meat requires much more energy (≈25:1)
Plants require far less energy (≈2:1)
More energy efficiency → more people can be supported
Therefore, plant-based diets allow more people to be fed
8. Give an example of a disproven scientific theory and how it was disproven.
Answer:
The phlogiston theory was disproven by Lavoisier through experiments showing combustion involves oxygen.
Explanation:
Phlogiston theory: substances release a substance when burned
Lavoisier measured mass and gases
Showed oxygen is consumed, not released
Led to modern chemistry and conservation of mass
9. Explain how new technology allows scientific theories to develop, with examples.
Answer:
New technology enables better data collection, allowing more accurate theories to form.
Explanation:
Rutherford used gold foil experiment (advanced detection) → discovered nucleus
Spectroscopy allowed scientists to observe atomic spectra → Bohr model
Without tools, these discoveries would not have been possible
10. Trace energy transformations: sunlight → trees → wood → steam engine → locomotive (20 m/s)
Answer:
Radiant energy → chemical energy → heat → mechanical energy → kinetic energy
Explanation:
Sunlight → captured by trees (photosynthesis)
Stored as chemical energy in wood
Burning wood → heat energy
Heat produces steam → mechanical motion
Engine converts motion → locomotive movement
11. Trace energy transformations: sunlight → evaporation → clouds → rain → waterfall → turbine → electric heater
Answer:
Radiant energy → thermal energy → gravitational potential energy → kinetic energy → mechanical energy → electrical energy → heat
Explanation:
Sun heats water → evaporation
Water rises → gains gravitational potential energy
Falls as rain → kinetic energy
Waterfall spins turbine → mechanical energy
Generator → electrical energy
Heater → thermal energy