Class Notes 2024

Plants and Animals

I. Plant Reproduction

A. Many use flowers, fruits, and seeds to reproduce

B.  Pollination in flowers occurs when stamen (male part) release pollen and it lands on the female part (pistil) resulting in fertilization (which produces a seed).

C. Germination occurs when a seed begins to sprout and grow.

D. Some plants produce fruit to protect seeds and help spread them. 

II. Vertebrate Sexual Reproduction (2 parents)

A. External Fertilization: sperm and egg join in watery environment (many fish and frogs/amphibians)

B. Internal Fertilization: sperm and egg join inside the female (mammals, reptiles, birds)

C. External Development: embryos develop within an egg outside the female body (most amphibians, reptiles, birds)

D. Internal Development: embryos develop within a pregnant female (mammals)

III. Other Reproduction Vocabulary Terms

A. Reproduction can be sexual (2 parents) or asexual (1 parent).  Types of asexual reproduction include: binary fission (single cell splits), budding (smaller offspring “buds” off from a parent), and spores (fungi or ferns release a cell that grows into offspring).

B. Metamorphosis occurs in some amphibians and insects.  This results in organisms changing forms over time (example: caterpillar→butterfly or tadpole→ frog).

C.  Placental refers to the formation of “placenta” which allows for nutrients to flow to developing offspring in mammals before they are born.

Natural Selection and Evolution

I. Populations Basics

A. A population is a group of the same type of organism living in the same area. Individuals within a population can have different traits.  

B. A population can be described by the traits present and by the number of individuals who have each trait (can be shown in a histogram)

C. Populations with a high variation of a trait have numerous types of individuals.  Populations with an even distribution of a trait will have similar numbers of individuals with that trait. 

II. Changes in Populations Over Time

A. Over many generations, individuals with adaptive traits become more common in a population, while individuals with non-adaptive traits become less common.

B. Whether or not a trait is adaptive depends on the environment.

C. Biologists analyze data about environmental conditions (the causes) to explain changes in the distribution of traits in populations (the effects).

III. Genes in Populations

A.  Individuals with adaptive traits are more likely to live longer and have offspring (and pass on their genes).

B.  Mutations (random changes) to genes can sometimes introduce new traits into a population. 

C. If new traits that form from mutations are adaptive, they can become more common in a population. 

IV. Natural Selection

A. Described by Charles Darwin (English Naturalist) in the Origin of Species (published in 1859).

B. Darwin describes how individuals with adaptive traits are more likely to survive and reproduce, passing on those traits to their offspring.  This can change populations over time. (Overproduction, Variation, Adaptation, Selection)

C. Darwin’s Theory replaces Lamarck’s idea of “Acquired Characteristics”, which stated that organisms pass on characteristics they gain over their lifetime (not true).  

(Example: Bodybuilders with large muscles cannot pass on muscles to their offspring)

V. Evolution

A. Change in species over time due to things like natural selection (explained by Darwin) and genetic mutation.

B. Some evidence of evolution includes:

-Fossils in sedimentary rocks (relative dating allows for scientists to estimate when certain organisms existed)

-Relatedness of species (shown in phylogenetic trees)

-Structures that are similar in different species which show a common ancestor (homologous structures)

-Some structures and behaviors that are no longer useful for some organisms can be identified (vestigial)

-Embryology (studying embryos and their development)

Genetics and Heredity

I. Deoxyribonucleic acid (DNA) 

A. DNA is passed from parents to offspring and contain instructions for building proteins, which cells use to grow, live, and perform other tasks.

B. It is in the shape of a double helix which contains four types of nitrogen bases, a deoxyribose sugar, and a phosphate molecule.  These parts combined are called a nucleotide. 

C. Strands are connected by a hydrogen bond and are paired up in the following way: Adenine (A) bonds with Thymine (T), Cytosine (C) bonds with Guanine (G).

D. If you know the order of nitrogen bases on one strand, then you should be able to identify the bases present in the complimentary (connected) strand.

II. Genes and Proteins

A. The section of DNA on a chromosome that codes for a protein or a trait (characteristic) is called a gene.  

B. Proteins are made of units called amino acids that are linked together in a certain order.  If the order of the amino acids changes, then protein that is made may change.

C. If a change occurs in a gene or chromosome, then it is called a mutation (which may affect the traits of an organism).

III. Modern Genetics

A. Selective breeding produces organisms with desired traits

B. Cloning produces copies of cells, tissues, organs, or organisms

C. Genetic engineering transfers genes between organisms

D. Analyzing genomes allows all genes within organisms to be identified (example=Human Genome Project)

IV. Heredity and Dominant/Recessive Inheritance

A. Heredity is the passing of traits from parents to offspring.

B. Patterns first identified by Gregor Mendel (Father of Genetics) using pea plants in mid 1800’s.

C. Dominant allele masks the recessive allele

D. Example using Pea Plants:

      Alleles for height:  T= tall  , t=short

         TT= homozygous or purebred tall

       Tt= heterozygous or hybrid tall

       tt= homozygous or purebred short

E. Punnett Squares allow for probabilities of traits to be determined.  They can predict rates of phenotypes (observable traits) and genotypes (genes or alleles) in offspring.

V. Other Inheritance Patterns

A. Incomplete Dominance: hybrids appear as a “blend”

B. Codominance: neither allele is dominant

C. Polygenic inheritance: a group of genes act together to produce a trait (not one gene)

D. Sex-linked traits or conditions: located on the X or Y chromosome which determines biological gender

-Often shown on a Pedigree which can allow for the tracing of a trait through a family.  

Cells and Cell Processes

I. Cell Theory and Cell Basics

A. Cell theory states that living organisms are made of cells (the units of life) that come from other living cells.

B. Prokaryotic cells (bacteria) are unicellular organisms without a nucleus.  Eukaryotic cells do have a nucleus where the DNA is contained (they can be unicellular or in multicellular organisms).

C. Examples of eukaryotic organisms include plants, animals, fungi (yeast, mushrooms), and protists (algae, amoebas).

D. Order of organization from smallest to largest in multicellular organisms:

Cells→ Tissues→ Organs→ Systems→ Organisms

II. Eukaryotic Cell Organelles and Plant vs. Animal Cells

A. Organelles are smaller parts of cells that have specific functions (roles they play).

B. Key organelles or cell parts include:

*Nucleus: control center (contains DNA)

*Cytoplasm: gel like material that holds organelles

*Cell Membrane: protects and allows materials in and out

*Ribosomes: makes proteins (protein synthesis)

*Vacuoles: stores water, food, and waste

*Mitochondria: powerhouse of the cell (breaks down food)

C. Plant Cells contain the following (which animal cells do not): Cell Walls (protection), Chloroplasts (which have chlorophyll for photosynthesis), and large central vacuoles.  

III. Mitosis (Cell Division)

A. One parent cell produces two identical new daughter cells with the same number of chromosomes (pieces of DNA) as the parent cell.

B. Interphase is 90% of the cell’s life and is when DNA is copied. Then Mitosis occurs (prophase, metaphase, anaphase, telophase).  Cytokinesis is when the two cells finally  separate. 

C. During cell division, centrioles are only present in animal cells and cell plates are only present in plant cells.

IV. Meiosis and Reproduction

A.  Meiosis forms gametes (male sperm cells and female egg cells) within an organism.

B. 2 divisions take place so that the cells that are produced have half the number of chromosomes as the body cells of the organism. 

C. Fertilization occurs when a sperm cell and egg cell combine to form a zygote.

D. The zygote will form more cells and grow over time through mitosis.

V. Photosynthesis and Cell Respiration

A.  Photosynthesis occurs when producers use light energy to produce glucose using chlorophyll/chloroplasts.  

Carbon Dioxide + Water +Light energy→ Glucose and Oxygen

6CO2 + 6H2O + light energy  →   C6H12O6    +  6O2

B. Cell Respiration occurs when producers AND consumers release energy (ATP) from glucose using the mitochondria.

Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)

C6H12O6 + 6O2 →  6CO2 + 6H2O + Energy (ATP)

Chemistry and Ecology

I. Atomic Structure and Periodic Table

A. Atoms are made of subatomic particles called protons, neutron, and electrons.  Protons (1 amu)  are positive, Neutrons (1 amu) are neutral, and electrons (0 amu) are negative. 

B. Elements (made of 1 type of atom) are identified on the Periodic Table and are arranged in order of Atomic Number (the number of protons or electrons).  Atomic mass is the number of protons and neutrons in an atom. When elements combine they form compounds (example: H2O)

*Groups are vertical (up and down) and periods are horizontal (across) in the periodic table.

C. Atomic Theory states that all matter is made of atoms, and that different elements are made of different types of atoms. Many scientists have contributed to this theory over time through experimentation.  

II. Physical and Chemical Changes

A. A physical change occurs when a material changes without a chemical reaction (change in shape, phase, color).  Examples: cutting objects, boiling/freezing/melting water, painting an object a different color

B. A chemical change occurs when a new substance forms through a chemical reaction.  It can be shown as a formula: 

Reactants→ Products (Example:  CH4 +      2O2          →          CO2      +      2H2O)   

                                            (Methane +  Oxygen     yields     Carbon Dioxide + Water)

Examples: burning, cooking/baking, creating gas by mixing chemicals, digesting food, rust forming, food rotting/spoiling

C. The Law of Conservation of Mass states that the total number of each atom has to be the same before and after a reaction (matter is

not created or destroyed)               

III. Ecosystems and Cycles of Matter

A. An ecosystem includes the community of organisms (biotic factors) in an area along with the nonliving surroundings (abiotic factors).

B. Matter in an ecosystem includes water, carbon, nitrogen, and many other substances.  These materials cycle over and over again (water cycle, carbon cycle, nitrogen cycle). 

C. Key terms for these cycles include:

*Water cycle: evaporation, condensation, precipitation, collection

*Carbon cycle: carbon dioxide, photosynthesis, atmosphere, fuel

*Nitrogen cycle: nitrogen fixation, decomposition, air, fertilizer

IV. Food and Energy in Ecosystems

A. Organisms may be producers (make their own food), consumers (eat other organisms), or decomposers (break down dead organisms).

B. Food and energy links among organisms can be shown in food chains and food webs (multiple food chains).

*Both always start with producers, then come consumers, and then decomposers

C. Energy pyramids show that there is less energy available at each level of a food chain or food web (there needs to be more producers than consumers for an ecosystem to be stable).

V. Human Impacts on Ecosystems

A. Some challenging effects of human actions include the following:

-Pollution/Emissions (acid rain forming and carbon dioxide being released from burning coal and oil)

-Deforestation (disturbing or cutting down wooded areas)

-Overhunting/overfishing for food or other resources

B. Some positive steps humans have taken to reduce impacts include the following:

-Replanting forest areas

-Using alternate and cleaner energy sources (that limit the release carbon dioxide)

-Conserving species and ecosystems

-Recycling (reusing materials)

Microscopes and Measurement

I. Compound Light Microscopes Basics

A. Magnifies objects or organisms using light and 2 lenses

B. The lenses include: eyepiece lens, scanning power objective lens, low power objective lens, and high power objective lens

C. To calculate the total magnification, multiple the eyepiece lens by whichever objective lens is being used at the time.

D. The field of view is the diameter across the area that is being observed and is often measured in millimeters (it will allow you to estimate the length of an organism)

II. Microscope Parts and Use

A. The lenses magnify images and the light source is plugged in to produce light

B. The stage is where the slide is placed for viewing (stage clips can be used if needed).

C. The diaphragm (under the stage) adjusts the amount of light and can darken or lighten the image.

D. Adjustment knobs are used for focusing

      *Coarse adjustment is larger and used to quickly bring something into focus (should only be used under scanning and low power)

      *Fine adjustment is smaller and used to sharpen the image (can be used under all objective lenses)

III. Length and Volume

A. Length is the distance between two points and is often measured in millimeters, centimeters, meters, and kilometers (longer distances).

B. Volume is the amount of three dimensional space and object takes up and is often measured in cm3 or milliliters (liquids).  

*For cubes and squares use the formula Volume=Length x Width x Height.  

*For irregularly shaped objects use a graduated cylinder (water displacement method).

IV. Mass and Temperature

A. Mass is the amount of matter (particles) in something. 

*Mass can be found using scales or triple beam balances

*Grams will often be the unit used for lighter objects and kilograms are used for heavier objects.

B. Temperature is a measure of hotness or coldness (it is actually a measure of average movement of particles)

*Celsius and Fahrenheit scales are commonly used

*Celsius scale (more common in science) is based on water.  The melting point of water is 0 degrees Celsius and the boiling point of water is 100 degrees Celsius.

Organisms and Scientific Method

I. Observations and Inferences

A. Observations are made using the senses (sight, taste, touch, smell, hearing) 

B. Observations can be quantitative (numbers or measurements) or qualitative (colors, texture).

C. Inferences are conclusions based on observations.

II. Characteristics of Organisms (living things)

A. Includes the following: made of cells, use energy, maintain homeostasis, genetics (DNA), grow and develop, evolve (have adaptations), reproduce, respond to stimuli

B. Key terms include:

Homeostasis: the maintenance of a stable internal environment (examples: body temperature, heart rate) 

Adaptations: behaviors or structures that help organisms survive (examples: hibernating, gills, fur) 

Stimuli (stimulus): may cause a response

(examples: a hot stove, cold air, light)

Metabolism: converting food into energy 

III. Scientific Method

A. Series of steps taken to investigate a question or problem

B. Usually includes identifying a problem, researching, testing a hypothesis

-A hypothesis (if, then, because statement) is an educated prediction that can be tested by conducting an experiment. 

C. The last step is often to “form a conclusion” based on the data (information collected).

IV. Experiments (collecting data)

A. Contain only 1 independent variable (the difference between the groups or trials)

B. Contain a dependent variable (the observation that is measured)

C. Contain multiple control variables (stay the same in all groups or trials)

D. Valid (reliable) if they can be duplicated (repeated) by others, and the same result is found to occur.

V. Organizing Data (charts and graphs)

A. Charts list data or information in a logical order.

-On a chart, the independent variable is usually on the left and the dependent variable is usually on the right

B. Graphs show trends visually (in science line graphs and bar graphs are common) 

-On a graph, the independent variable is on the X axis and the dependent variable is on the Y axis 

-If the graph shows something occurring “over time”, then time goes on the X axis.