Living Environment Exam Study Guide

Unit 1: Science and the Living Environment

A. Terms

1. Observation: What is seen or measured directly.
2. Inference: A conclusion drawn from observations or evidence.
3. Hypothesis: A testable prediction based on available evidence, stating both cause and effect. It can be written as an "if-then" statement. For example, "If I give patients this pill, then they will not get sick."
   • A good hypothesis can be tested and proven incorrect through experimentation.
4. Theory: A well-supported explanation of natural events, backed by substantial evidence, scientific facts, hypotheses, and laws.
   • It is important to note that in science, a theory is not a mere guess, but a robust explanation.

B. Controlled Experiment

Controlled experiments compare results between two or more groups:

1. Experimental Group: The group receiving the treatment or being tested.
2. Control Group: The "normal" group, identical to the experimental group in all aspects except it does not receive the treatment. A placebo (sugar pill or fake treatment) may be given to this group.
3. Placebo: A “fake” treatment given to the control group.
4. Independent Variable: The variable being tested. It is the "If" part of a hypothesis and is plotted on the X axis.
5. Dependent Variable: The variable that is measured; the results. It is the "then" part of a hypothesis and is plotted on the Y axis.

C. Graphs and Data Tables

1. Data Tables:
   • Organize data for graphs.
   • The first column is for the independent variable, and the second is for the dependent variable.
   • Columns should be titled with units of measurement.
   • Data must be arranged in ascending or descending order.
2. Graph Axes:
   • Both x and y axes must be labeled/titled, matching the data table, including units.
   • The independent variable is on the x-axis, and the dependent variable is on the y-axis.
   • Number axes with uniform increments that take up most of the axes.
   • Numbers should align with grid lines.
3. Line Graphs:
   • All graphs on the Living Environment Regents have been line graphs.
   • Points must be surrounded by a circle, square, or triangle.

D. Characteristics of a Good Experiment

1. Repeatability: The experiment can be repeated with the same results.
2. Sample Size: A large sample size or many test subjects.
3. Duration: Performed for a longer period of time.
4. Single Independent Variable: Only one independent variable is tested.
5. Peer Review: Examined by several scientists.
6. Objective: Fair and unbiased conclusion.
7. Ethical: Complies with ethical and legal standards.

Unit 2: Characteristics of Living Things

A. Chemistry

1. Common Elements: The most common elements in living things are Carbon, Hydrogen, Oxygen, and Nitrogen (CHON).
2. Organic Compounds:
   • Contain both Carbon and Hydrogen (e.g., $C<em>6H</em>{12}O<em>6$ is organic, $H</em>2O$ is not).
   • Organic molecules are larger than inorganic ones.
3. Carbohydrates: Sugars and starches that provide energy. They are made from simple sugars like glucose.
   • Enzymes break down complex sugars into simple sugars.
4. Lipids: Store energy and include fats, oils, and waxes.
5. Proteins: Made from amino acids and are crucial for building and running an organism’s body.
   • The shape of a protein determines its function.
   • Specific jobs of proteins:
     1. Enzymes
     2. Receptor molecules on the cell membrane (receive chemical messages like hormones)
     3. Antibodies (fight infection)
     4. Hormones (chemical messengers)

Enzymes

1. Enzymes are catalysts made from protein.
   • Catalysts affect reaction rates.
   • Lock and key model - one enzyme fits one molecule. Change the shape and the enzyme will no longer work.
   • High temperatures denature enzymes.
2. pH:
   • Acidic: pH 0-6
   • Neutral: pH 7 (water)
   • Basic: pH 8-14

B. Homeostasis

1. Homeostasis: A balanced state in an organism.
2. Dynamic Equilibrium: Maintaining balance by taking action when disturbed (e.g., sweating when hot).
3. Life Functions: Organisms carry out transport, nutrition, excretion, respiration, growth, synthesis, and regulation to maintain homeostasis.
4. Metabolism: All life processes.
5. Failure to maintain homeostasis leads to disease or death.

C. Transport

1. Diffusion: Movement of molecules from high to low concentration; requires no energy (passive transport).
2. Active Transport: Requires energy to move molecules from low to high concentration (against diffusion).
3. Osmosis: Diffusion of water into or out of the cell causing swelling or shriveling depending on the direction of water movement.

D. Nutrition

1. Autotrophs make their own food, heterotrophs eat other organisms.
2. Photosynthesis:
   • Plants, algae, and blue-green bacteria (autotrophs) convert radiant energy into sugar molecules. Occurs mostly in the chloroplasts of plant cells.
   • Stomates in leaves exchange gasses. Guard cells control stomate opening/closing to prevent dehydration.
   • Xylem and phloem transport food and water.

E. Respiration

1. Process that takes energy from sugar molecules and places it in molecules of ATP. ATP is the energy source of all living things.
   • Aerobic respiration (with oxygen) yields more ATP than anaerobic respiration (without oxygen).
   • Anaerobic respiration in humans produces lactic acid that damages muscles.
   • Photosynthesis and Aerobic Respiration are opposite reactions.

F. Regulation

1. Coordination and control of other life functions.
2. Stimulus: A change in the environment that you respond to.
3. Neuron: A nerve cell.
4. Impulse: The electrical signal carried by the nerves. Neurotransmitters are chemicals that help carry the impulse.
5. Hormone: A chemical signal secreted by different glands in the body. Examples of hormones include insulin, adrenaline, testosterone and estrogen
6. Receptor molecules are proteins on the surface of the cell membrane that receive signals from the nervous and endocrine system. These are needed for your cells to communicate and work together.
   • As with all proteins, it is the shape of the receptor molecule that determines its functions (in this case, which signals it receives).

G. Cells

1. Cells are the basic unit of life. All living things (except viruses) are made of cells.
2. Cell Theory:
   • All living things are made of cells.
   • Cells carry out life functions.
   • All cells come from other cells.
3. Organelles: Cell membrane, cell wall, nucleus, chloroplast, cytoplasm, ribosome, vacuole, mitochondria, etc.
4. Plant vs Animal cells
   • Plant cells have cell walls, animal cells do not.
   • Plant cells have chloroplasts, animal cells do not.
   • Animal cells have centrioles, plant cells do not.
   • Animal cells usually have many small vacuoles, plant cells usually have fewer, larger vacuoles.
5. Cell Membrane: Made of lipids and proteins, selectively permeable.
   • Small molecules ($O<em>2$, $H</em>2O$, $CO_2$, sugars) pass freely through the cell membrane through diffusion.
   • Large molecule (proteins, starches) cannot pass through the cell membrane without the help of transport proteins.
   • Active transport uses energy (ATP) to move a molecule.
   • Basic types of proteins in the cell membrane:
     • Receptor proteins
     • Transport proteins
     • Antigens

Unit 3: Homeostasis and the Human Body

A. Organization

1. Cells are specialized into tissues.
   • Tissues grouped cells: muscle tissue/nerve tissue
   • Specialization/differentiation changes a stem cell into a specialized tissue.
   • Cells have the same genes; only needed ones are "turned on".
   • Stem cells haven't been specialized.
2. Tissues form organs.
3. Organs form organ systems.

B. Nervous System

1. Regulates body with electrochemical impulses.
2. Spinal cord: reflexes, relays impulses brain/body.

C. Endocrine System

1. Uses hormones (insulin, adrenaline, testosterone, estrogen)
2. Slower but longer-lasting effects vs nervous system.
3. Pancreas makes insulin and glucagon to control blood sugar.
4. Adrenal glands makes adrenaline when the body is under stress.
5. Testosterone (male), estrogen and progesterone (female) are the sex hormones. These are made in the gonads (testes for males, ovaries for females).
6. Hormone levels are controlled by feedback mechanisms.

D. Transport/Circulatory System

1. Moves materials through the body.
2. Heart pumps.
3. Red blood cells carry oxygen, white blood cells fight disease, platelets clot blood, and plasma transports everything except oxygen.

E. Respiratory System

1. Breathing provides oxygen for respiration and excretes $CO_2$.
2. Diaphragm facilitates breathing.
3. Breathe faster when $CO_2$ builds up, not when needing oxygen.
4. Alveoli enable oxygen entry and CO2 exit in the blood, surrounded by capillaries.

F. Immune System

1. Protects against pathogens.
2. Pathogens: viruses/bacteria/parasites.
3. White blood cells (w.b.c’s):
   • Identify, tag, destroy pathogens.
   • Make antibodies.
4. Antigens are protein “tags” on that can be used to identify a cell or virus. Cells and viruses which have antigens different than yours will cause an immune response.
5. Antibodies attack antigens; specific to shape.
   • Organ transplant rejection.
   • Blood type O is a universal donor; type AB is the universal acceptor.
6. Vaccines inject dead/weakened pathogen: promote antibody production; prevent, do not cure.
7. Antibiotics fight bacteria; not viruses; can cure diseases.

G. Excretory System

1. Removes metabolic waste (salt, water, urea, $CO_2$).
2. Lungs excrete $CO_2$ and water, skin excretes sweat.
3. Kidneys filter wastes/reabsorb nutrients.
4. Liver filters toxins and dead red blood cells.

H. Digestive System

1. Breaks down food for cell entry.
   • One-way passage: mouth, stomach, intestines.
   • Peristalsis moves food.
   • Mechanical/chemical breakdown.
   • Undigested food is eliminated as solid waste (feces).

I. Interaction Between Systems

1. Nutrients digestive system -> cells (circulatory).
2. Respiratory wastes -> excretory system.
3. Nervous/Endocrine: control body.
4. Immune protects nervous.
5. Digestive gives nutrients to endocrine.

J. Diseases and Disorders

1. Aids, Cancer, Diabetes, Allergies

Unit 4: Reproduction

A. Asexual Reproduction

1. Advantages: faster, easier.
2. Disadvantage: no variety.

B. Sexual Reproduction

1. Advantage: variety via gene recombination.
2. Disadvantage: more time, effort, and risk incurred.

C. Mitosis

1. Asexual reproduction.
2. Daughter cells' number and types of chromosomes = parent cell.
3. Large organisms use mitosis for growth and healing. Simple organisms use it to reproduce.
4. One division -> two identical, diploid (2n) cells.

D. Meiosis

1. Makes gametes for sexual reproduction.
2. One cell divides twice -> four DIFFERENT haploid (1n) cells.
3. Pair separates homologous chromosomes: offspring get one chromosome per pair from a different parent.
4. Daughter cells get half the chromosomes of the parent cell.

E. Male Reproductive System

1. Testes make/store sperm.
2. Testosterone: male sex hormone.

F. Female Reproductive System

1. Ovaries produce eggs.
2. Menstrual cycle lasts 28 days (average).
   • Ovulation occurs
   • Menstruation- shedding of the uterine wall
   • Pregnancy: cycle stops.
3. Fallopian tube carries eggs to the uterus.
4. Uterus is where baby develops.
5. Vagina: baby exits (birth canal).

G. Fertilization

1. In the fallopian tube (oviduct).
2. Fertilized egg is a zygote.
3. Restores chromosome set: zygote is diploid (1n + 1n = 2n chromosomes).

H. Development

1. Zygote develops into embryo then fetus.
2. Placenta transfers nutrients/oxygen from mother's blood to fetus's (no mixing).
3. Umbilical cord connects fetus to placenta.
4. Waste leaves fetus via placenta.
5. Embryo/fetus develop in the uterus/womb.
6. Cells divide without enlarging (cleavage).
7. Cells become different (nerve, skin, bone).
8. Embryo is susceptible to alcohol/drugs.

Unit 5: Genetics

A. Chromosomes

1. Humans have 46 chromosomes, or 23 homologous pairs.

B. Alleles

1. Chromosome pairs carry alleles for same trait.

C. Sex Chromosomes

1. Females are XX; males are XY.
2. Y chromosome is smaller: males have single gene for some traits, such as color blindness, called sex-linked traits.

D. Environment

1. Environment affects gene expression.

E. Genes

1. Each chromosome has hundreds or thousands of genes.
2. Each gene codes for a protein.

G. DNA and Bases

1. DNA bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G).
2. Three-letter codon represents amino acid -> proteins.

H. Base Pairs:

1. A-T and C-G (in RNA, A-U and C-G)

I. Protein Synthesis

1. RNA carries code to ribosomes-> protein.

J. Mutations

1. DNA changes are mutations, which only pass on if in sperm/egg.
2. Mutagens: are radiation, chemicals, and viruses.
3. Mutations change protein structure.

K. Gene Activation

1. All cells have same genes, just some turned on; reasons vary.

L. Genetic Technology

1. Selective breeding: animals/plants desired traits.
2. Genetic Engineering (gene splicing):
   • Insert genes from one organism genes into another; enzymes cut/copy DNA.
   • Bacteria used (no nucleus, fast reproduce): make insulin.
   • Human insulin gene inserts into bacteria, bacteria then make insulin like humans
3. New tech (karyotyping/DNA fingerprinting) diagnoses genetic diseases, but no cure.

M. Ethics

1. Genetic research: raises ethical issues.

Unit 6: Evolution

A. Modern Species

1. Evolved from earlier species, sharing a common ancestor.

B. Natural Selection

1. Darwin: natural selection is the mechanism for change.
2. Steps:
   • Overproduction offspring + variation.
   • Competition limited resources: variations impact outcomes.
   • Survival gene passing or death no passing.
   • Beneficial variations pass/become common.

C. Fitness

1. "Fit" organisms are adapted and reproductive.
2. "Unfit" die without gene pass.
3. Evolutionary fitness is not physical fitness.
4. Fitness is determined by who is better adapted to survive in a particular environment and who can pass on their genes.

D. Environment

1. Evolution driven by change in environment/organisms in it.

E. Extinction

1. Species failing adaptation become extinct.
2. Low variation: cannot adapt.
3. Individual organisms die; they cannot go extinct. Only species can become extinct.

F. Variation and Adaptation

1. Variations must exist before environment change (pre-adaptation).
2. Giraffes evolved long necks because the ones with longer necks were better adapted to get food than short neck giraffes

G. Variation Sources

1. Variations: sexual reproduction and mutation provide.

H. Diversity

1. Greater variation: better chance of environmental change survival.

I. Gradualism vs. Punctuated Equilibrium

1. Gradualism is the idea that says evolutionary change occurs slowly. Punctuated equilibrium says evolution happens in “quick” bursts.

J. Isolation

1. New species need geographical separation and reproductive isolation.

K. Evidence

1. Evolution evidence stems from geology, genetics, biochemistry, anatomy, embryology.

L. Classification

1. Organisms classified based on evolutionary relationship.
2. Kingdoms: large organism groups.
3. Species: can reproduce.
4. Cladograms depict relationships.

Unit 7: Ecology

A. Interactions

1. Understand how organisms interact with their environment (food webs, nutrient cycles).

B. Energy Input

1. Energy is needed to keep an ecosystem going. The energy comes from the sun and is made usable by producers (plants and other autotrophs)

C. Energy Loss

1. Energy is passed on to other organisms in the form of food. Since all organisms must use energy for their own needs, most energy is lost before it can be passed to the next step in the food chain. As a result, organisms high on the food chain have less energy available to them and must have smaller populations (see energy pyramid).

D. Environmental Factors

1. Environmental factors (air, water, light, temperature, pH, food, predators etc) determine which organisms can live in an ecosystem and how large the population can get.
2. Carrying capacity: population size max.

E. Niche Partitioning

1. Competition usually results only in one species per niche.

F. Ecological Succession

1. Know the basic processes of ecological succession.

G. Ecology Terms

1. producer, consumer, omnivore, herbivore, carnivore, predator, parasite, habitat, niche, population, community, ecosystem, biosphere, pollution, renewable resource

H. Human Impact

1. Human action often has negative consequences for the ecosystem
2. the increasing human population.

J. Biodiversity

1. Variety of life on earth; reduces with lost habitat/species.
2. Consequences of low diversity:
   • Ecosystem low stability
   • Ecosystem needs longer recovery
   • We lose resources

K. Action to Help

1. Repair damage to the environment.
2. Recycling wastes.
3. Conserving available resources.
4. Using cleaner resources.

L. Ecological Problems

1.Be able to identify the specific cause, their negative effects on the environment, and a way that people are trying to fix the problem:
* Acid rain
* Loss of habitat (ex: deforestation)
* Loss of diversity
* Global warming
* Loss of ozone layer
* Introduced species
* Industrialization

Appendix: State Labs

A. Making Connections (Clothespin Lab)

1. Part A1
   • Exercise and Rate
   • Exercise increase pulse rate
2. Part A2
   • Squeezed a clothespin for 1 minute
   • May have been because your finger muscles were “warmed up” from increased circulation.
   • May have been because your finger muscles were fatigued.
3. Part B
   • How to design an experiment (see pages 3-5).

B. Relationships and Biodiversity (Botana curus lab)

1. What you did: Compared 4 species of plants, based on structural (physical) and molecular (chemical and genetic) traits.
2. What you learned:
   • Species that are related share similar traits.
   • Different techniques (such as gel electrophoresis and paper chromatography) can be used to determine relationships between organisms.
   • Endangered species should be protected because they may offer benefits to humans.

C. Beaks of Finches

1. What you did: Played different finch species competing for food.
2. What you learned: Different environmental conditions (food) favored different species of finch, allowing some to survive and reproduce, but not others.

D. Diffusion Through A Membrane

1. Part A
   • What you did:
     1. Made a model cell using dialysis tubing.
     2. Put glucose and starch inside your “cell.”
     3. Put starch indicator (iodine) outside cell.
   • What you saw:
     1. Inside of cell turned black because iodine diffused into the cell.
     2. Because outside of the cell was not black, you know the starch did not diffuse through the membrane.
     3. Used blue glucose indicator (Benedict’s solution) to see that glucose did diffuse through the membrane.
   • What you learned
     1. Small molecules (glucose, iodine) can diffuse through a membrane on their own.
     2. Large molecule (starch) cannot diffuse through a membrane on their own.
     3. You can use indicators to identify the presence of specific substances.
2. Part B
   • What you did:
     1. Looked at red onion cells under the microscope.
     2. Added salt water to the onion cells.
     3. Added distilled (pure) water to the onion cells.
   • What you saw:
     1. Salt water caused the onion cells to shrivel.
     2. Distilled water cause the cells to swell back to normal.
   • What you learned:
     1. Salt water causes water to diffuse out of a cell.
     2. In pure water, water will diffuse into a cell.