Biology Mid-Term Review 2025 PDF

Mid-Term Review Packet January 23rd, 2025 12:30 pm  The Microscope Compound Light Microscope: 1.​ Ocular – (eye piece) look through, magnifies the image. 2.​ Body Tube - holds lenses 3.​ Nosepiece - rotates the objectives (lenses) 4.​...

Mid-Term Review Packet January 23rd, 2025 12:30 pm  The Microscope Compound Light Microscope: 1.​ Ocular – (eye piece) look through, magnifies the image. 2.​ Body Tube - holds lenses 3.​ Nosepiece - rotates the objectives (lenses) 4.​ Stage – platform for slides. 5.​ Stage Clips - holds slide in place 6.​ Diaphragm - controls the amount of light passing through the specimen 7.​ Mirror or Light Source (illuminator) - lights the specimen so it is easier to observe 8.​ Arm – used to carry the microscope 9.​ Base - supports the microscope 10.​ Coarse Adjustment Knob - used for preliminary focusing, NEVER used on high power. 11.​ Fine Adjustment Knob – used to focus on high power, and to fine tune low power. 12.​ High Power Objective: This objective has a magnification oLow Power Objective: This objective has a magnification of 10x (minimum magnification 100x (maximum magnification) How to find Total Magnification: Ocular Lens (10x) x Objective Lens = Total Magnification Example: 10x times 4x = 40x Ultracentrifuge: Separates cell parts (organelles) by spinning them in a test tube at high speed (denser parts sink to the bottom of the test tube). FIeld of View (FOV): ​ Millimeter = mm ​ Micrometer = µm ​ 1000 µm = l mm ​ 1 µm = 1/l000 mm Size of Object = ____FOV______ Number of Objects that fit across the FOV.  Scientific Method What is it? Scientists follow a set of steps in order to answer questions about the world around them. There are seven steps to follow... 1. Identify the Question or Problem - What are you trying to find out? Can you make an experiment to research this problem? - Create a question. 1a. Research the Question or Problem 2. Form a hypothesis - An educated guess. It is what you think will happen. - The hypothesis is specific to the question. It is always a statement. - Using an If, then statement. DO NOT use I, we, you in your hypothesis. 3. Design an Experiment ​ - What materials will be used and what safety precautions will be followed? - How will you collect data? 4. Collect Data ​ - Observations, can be measured in numbers (quantitative data) and description (qualitative data). 5. Organize and Analyze Data ​ - Using tables and graphs 6. Form a conclusion - What happened in your experiment? - Does the data support or refute the hypothesis? 7. Future experiments - Did the experiment’s conclusion lead to more questions? The cycle can begin again.  ** To make an experiment more reliable, you retest (perform the experiment again)! ** Independent Variable: The part of the experiment that is controlled by the person conducting the experiment. -​ “I” can change the independent variable. Dependent Variable: The data that is being collected in the experiment. **When graphing, the Independent variable goes on the x-axis and the Dependent variable is on the y-axis. ** Graphing Graphing: In order to receive full credit for a graph, the following must be present... 1. A title: This shows what the graph is about. It should be short and to the point. 2. Label X-axis and Y-axis. 2. Independent Variable: The part of the experiment that changes. It can be controlled or manipulated by the experiment. It goes on the X- Axis. 3. Dependent Variable: The variable that is observed and that changes in response to the independent variable. It is the result of what happens. On y-axis. 4. Scales: Each block on the graph should have its own scale. Should be a consistent number or increment on the axis. For example: BY.5, 1, 5, 10, 20 5. Key: Make a key if you are graphing more than one subject. Important! - You always need to start from zero when graphing. - DO NOT connect zero unless it is graphed.  The Cell The Cell Theory and The Exceptions Cell Theory: 1. All organisms are made up of one or more cells. 2. These cells working individually, or together in tissues or organs, perform all life functions. 3. All cells come from pre-existing cells. The Exceptions: 1. The first cell could not have come from a pre-existing cell. 2. Viruses - which are not cells have hereditary material and can reproduce. 3. Organelles such as mitochondria and chloroplasts have genetic material (DNA) and can reproduce. Plant and Animal cell organelles structure (what do they look like, where are they located) and function (what do they do?) 1. Cell Organelles: Small special structures that carry out life functions. 2. Cell "Plasma" Membrane: Regulates the movement of materials into or out of cells. It is semi-permeable. 3. Cytoplasm: Jelly like environment. The movement of the cytoplasm is called cyclosis which transports materials throughout the cell. 4. Nucleus: Controls cell activities and is surrounded by nuclear membrane. Contains genetic material (DNA and RNA). Involved in Reproduction! 5. Mitochondria: Site of cellular respirations (C6H12O6 + O2 ---> CO2 + H2O + ATP). Produces energy. 6. Golgi Complex: Synthesizes (makes), packages and secretes (releases) cellular products. 7. Ribosomes: Synthesis of proteins. 8. Endoplasmic Reticulum: Forms passages throughout the cell for intracellular (within the cell) transport. ​ Two Types: 1. Smooth ER: No ribosomes 2. Rough ER: Covered in ribosomes 9. Vacuole: Space in a cell surrounded by a membrane. - Food vacuole - stores food to be digested.  - Contractile vacuole – helps to maintain water balance within a cell. ONLY IN ANIMAL CELLS: 10. Centrioles: Play a role in cell division. 11. Lysosome:Contains digestive enzymes (breaks down damaged organelles or pathogens). ONLY IN PLANT CELLS: 12. Chloroplasts: performs photosynthesis (making nutrients). (CO2 + H2O + ATP ---> C6H12O6 + O2 ) 13. Cell Wall: non-living structure that surrounds, supports and protects the cell. Made of cellulose (a polysaccharide). 14. Large Vacuole: Stores water for the cell.  Mitosis -Leads to the production of two new cells called daughter cells. ​single-celled organisms = ASEXUAL REPRODUCTION ​The daughter cells grow and increase in size until they divide and produce two more daughter cells. ​Multicellular Organisms = BODY cells are produced by mitotic cell division. Phases of Mitosis: Interphase: "Rest" ​ Cell grow in size and carry on metabolism. ​ Chromosomes duplicate and prepare for cell division. (PMAT) Prophase: ​ The double-stranded chromosomes become visible ​ The nuclear membrane disappears. ​ A spindle apparatus, consisting of fibers, forms between opposite poles of the cell. Metaphase: ​ Centromeres are lined up along the equator (middle) of the cell Anaphase: ​ Chromosomes are pulled to opposite ends of the cell. Telophase: ​ Chromosomes at poles ​ Nucleus and nucleolus reappear CYTOKINESIS: At the end of mitosis, the cytoplasm divides, forming two new identical daughter cells.  Diffusion Diffusion (Passive Transport) and Active Transport Concentration: The amount of a substance compared to water - High Concentration = A LOT of substance - Low Concentration = SMALL amount of substance Diffusion (Passive Transport): Molecules move from areas where there is high concentration to areas where there is low concentration. ** HIGH TO LOW IS THE NATURAL FLOW!!!** Active Transport: Molecules are very large and need the help of energy (ATP) to move across membrane. Move from areas of low concentration to areas of high concentration. Osmosis: The diffusion of water. ​ - Pure water, water enters the cell. ​ - Salt water, water leaves the cell.  Diffusion Through a Membrane NYS Lab Part One: Iodine (is an amber color): is an indicator for starch. ​ - It is like the blue/black flag for starch. When starch is present or is there, we see an blue black color (flag). Benedicts Solution (is a blue color): is an indicator for glucose (a sugar). (HAS TO GO IN HOT WATER BATH FOR TESTING). ​ - It is an orange flag for glucose. When glucose is present or is there, we see a orange (flag). In the lab we made a cell with starch and glucose substance that was put inside of the cell. We then placed the cell in water with iodine mixed inside. It looked like this.. I = Iodine (starch indicator) G = Glucose S = Starch ​ ​ - We let the cell sit inside of the water and iodine mix for about 15/20 minutes. - Looking at it 15/20 minutes later, we saw the cell was a blue/black color and the beaker remained the same, the amber color ​ We wanted to look at what was now inside of the cell and what was outside of the cell 15/20 minutes later. ○​ Was it the same? No. ​ ​  ​ How did we know this is what it now looks like? Well... ​ ​ - We know that glucose came out of the cell, because we took some of the outside water (the original amber and water mix) and put it in two separate test tubes. - Test Tube A: tested it with the Benedicts Solution (glucose indicator) and put it in a heat bath. ​ - Test Tube A: orange (GLUCOSE FLAG) - Test Tube B: tested with the Iodine (starch indicator). ​ ​ ​ ​ - Test Tube B: no change in color, stayed amber, no starch! What did this show: This showed that on the outside (in the amber and water mix) there was glucose present, meaning, glucose moved from where it was originally (inside of the cell) to outside of the cell. Starch stayed inside of the cell, did not leave the cell (MOLECULES ARE TOO BIG). ** In order to have balance, iodine had to also move inside of the cell because glucose moved out.** Part Two: 1. Osmosis is the movement of w molecules through a selectively permeable membrane into a region of higher concentration, in the direction that tends to equalize the solute concentrations on the two sides. 2. Water leaves the cell when salt water is present to a cell. 3. Water enters the cell when pure water is present to a cell. 4. A contractile vacuole expands and contracts. The point of the contractile vacuole is to pump water out of the cell. When a red onion cell is placed in a salt water solution, the water content decreases and water diffuses out of the cell. When a red onion cell is placed in pure "distilled" water solution, the water content increases and water diffuses into the cell.  Life Functions Life Functions (8 of them: 3R-GENTS) Respiration Regulation Reproduction Excretion Growth Nutrition Transport Synthesis Biology: The study of living things and their surroundings. Metabolism: All chemical reactions in an organism that make and use energy. Homeostasis: Maintaining a constant internal condition, regardless of the external environment. Respiration: Produces energy in the mitochondria. ​ Aerobic: Needs oxygen ​ Anaerobic: does NOT need oxygen Regulation: Control and coordination of life processes Reproduction: Production of offspring Growth: Increase in size Excretion: Removal of metabolic waste Nutrition: getting nutrients through food ​ Autotrophic: Makes their own food through photosynthesis ​ Heterotropic: Gets nutrients from the environment Transport: Organisms circulate and absorb materials through the cells Synthesis: To build from small to large Levels of Organization organelle --> cell --> tissue --> organs --> organ system --> organism Organelle: specialized structures that perform the 8 life functions in the cell Cell: unit of structure and function for all life Tissue: composed of groups of similar cells Organs: composed of groups of tissues functioning together Organ systems: composed of groups of organs functioning together Organism: composed of organ systems working together  Biochemistry Organic: Contain C and H Inorganic: Usually "support" life, contains C or H Mixture: Is a material composed of two or more elements or compounds that are physically mixed. Solution: a type of mixture where all of the components are evenly distributed. Has two parts: ❏​ Solute: Substance that is being dissolved. ❏​ Solvent: The substance in which the solute dissolves. Formula Structural Formula: Line drawings of the compound that shows the elements in proportion and how they are bonded. Example: H-O-H (Water) Molecular Formula: the ACTUAL formula for a compound. Example H2O Acids & Bases Acids: 1-6 on pH scale. Bases: 8-14 on pH scale. pH: measures degree of substance alkalinity or acidity. Alkalinity: The capacity of water to resist changes in pH that would make the water more acidic. Buffers: Add weak acids & bases to prevent sharp changes in pH. Organic Compounds (Carbohydrates, Proteins, Lipids, Nucleic Acids) Carbohydrates:a key source of ENERGY! They include sugars and complex carbs (starches). ​ - Building blocks = simple sugars! ❏​ Monosaccharide (simple sugar): SINGLE ring structure, all have C6H12O6 (glucose). ❏​ Disaccharide: All formulas have C12H22O11 (LOST A H2O MOLECULE), double ring. ❏​ Polysaccharide: Formed of three or more simple sugar units  ❏​ Glycogen - animal starch stored in liver & muscles ❏​ Cellulose - indigestible in humans - forms cell walls ❏​ Starches - used as energy storage ❏​ Dehydration Synthesis: Combining simple molecules to form a more complex one with the removal of water. ❏​ Hydrolysis: Addition of WATER to a compound to SPLIT it into smaller subunits. Lipids (Fats): Fats, oils, waxes, steroids. Mainly function in energy storage, protection, and insulation. They tend to be large molecules. ❏​ Building blocks are formed from the union of one glycerol molecule and 3 fatty acids. Proteins: Composed of MANY amino acid subunits. It is the arrangement of the amino acid that forms the primary structure of proteins. Function of proteins are growth and repair, energy, and helps keep body pH constant. ❏​ Dipeptide: Formed from two amino acid subunits by Dehydration Synthesis. ❏​ Hydrolysis of a Dipeptide: Breaking down of a dipeptide into amino acids ❏​ dipeptide + H2O ---> amino acid + amino acid ❏​ Polypeptide: Composed of three or more amino acids linked by synthesis reactions. Nucleic Acids: composed of nucleotides, store and transmit genetic information. ❏​ Nucleotides consist of 3 parts: 1. 5-Carbon Sugar 2. Phosphate Group 3. Nitrogenous Base ❏​ DNA (deoxyribonucleic acid): Contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins. ❏​ RNA (ribonucleic acid): Directs cellular protein synthesis. ❏​ CHEMICAL REACTIONS: A process that changes one set of chemicals into another set of chemicals ❏​ REACTANTS: elements or compounds that enter into a chemical reaction. ❏​ PRODUCTS: elements or compounds that are produced in a chemical reaction.  Enzymes and Enzyme Actions: Enzymes: Organic catalysts made of protein. ❏​ Most enzyme names end in -ase Catalyst: Inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself. Specific in:​ 1. pH 2. Shape 3. Temperature Substrate: Molecules upon which an enzyme acts. Lock and Key Theory: Each enzyme is specific for one and ONLY one substrate (one lock - one key). Important Structures/ Pictures Carbohydrates (starches): Monosaccharide: Disaccharide: Polysaccharide: Dehydration Synthesis:  (A water is removed H2O) monosaccharide + monosaccharide ----> disaccharide + water (C6H12O6 + C6H12O6 ----> C12H22O11 + H2O) Hydrolysis: ​ ​ ​ (Addition of water H2O) disaccharide + H2O ---> monosaccharide + monosaccharide Lipid (fats): Proteins: Carboxyl Group: Dipeptide:  amino acid + amino acid ----- dipeptide + water Hydrolysis of a Dipeptide: dipeptide + H2O ---> amino acid + amino acid Nucleic Acids: Bases: DNA: RNA: Enzymes: Lock and Key:  Genetics Genetics is the Study of heredity (the transmission of traits from generation to generation). Genotype: the genetic make up of an individual. ​ ex. TT, Tt, tt a. Homozygous – (pure) both alleles are the same ex. TT – tall ​ tt – short Pure = not mixed b. Heterozygous- (hybrid) possessing two different alleles for the same trait Hybrid = mixed Phenotype: The appearance of the offspring (you can see the phenotype). Gregor Mendel Gregor Mendel: Mendel began by cross-pollinating pure plants with contrasting traits. Mendel Founded... Segregation: Splitting of chromosomes during meiosis. Recombination: Combining chromosomes from both the sperm and egg (fertilization). Independent Assortment: Independent segregation of genes during the formation of gametes. ** Gametes egg and sperm cells** Mendel’s Law of Independent Assortment Two traits will be inherited independently of each other, provided their genes are located on non-homologous chromosomes. Law of Dominance: One form of a hereditary trait dominates or prevents the expression of the recessive trait. Codominance: some traits are controlled by 2 different dominant alleles. Both alleles are dominant, and there are two dominant phenotypes. Expresses both phenotypes at the same time. Incomplete dominance: (blending inheritance) sometimes an allele is only partly dominant over another. Gene Linkage: If the genes for two different traits are located on the same chromosome pair (homologous chromosomes), they are said to be linked, and are usually inherited together. Crossing over: In the 1st meiotic division the chromatids of homologous chromosomes may exchange segments. This results in the rearrangement of linked genes and increases variability of offspring. Multiple Alleles: some traits are controlled by more than 2 different alleles types. Sex determination: XX (Female) XY (Male). Determined by the sex chromosome (23rd pair). Karyotyping: The number and visual appearance of the chromosomes in the cell nuclei of an organism or species  Genetic Disorders: Phenylketonuria: PKU –There is an inability of the gene to synthesize the enzyme needed for the metabolism of the amino acid phenylalanine. Sickle Cell Anemia: Abnormal hemoglobin and sickle shaped red blood cells. Mostly in people of African descent. Difficulty transporting oxygen around the body. Tay Sachs: Nervous system malfunctions. Fatty material accumulates, and destroys nerves, due to the inability to synthesize a specific enzyme  Modern Genetics DNA: Deoxyribonucleic Acid. DNA is the molecular basis for heredity. Contains the specific instructions to specify characteristics. DOUBLE STRANDED. Double Helix: Resembles a ladder. Alternating phosphate groups. Rungs are composed of alternating bases held together by weak hydrogen bonds. ( Watson and Crick) Building blocks: ​ 1. Phosphate Group 2. 5 Carbon Sugar DNA = Deoxyribose RNA = Ribose 3.Nitrogenous Base A - Adenine T - Thymine C- Cytosine G- Guanine ** AT Garden City** A=T C= G RNA: The sugar is RIBOSE. URACIL (U) is substituted for (T) Thymine. RNA is a single stranded chain of nucleotides. A=U C=G  Types of RNA mRNA (messenger RNA): Reads the information on the DNA and carries the MESSAGE from the nucleus to the ribosome in the cytoplasm to the ribosome. tRNA (Transfer RNA): Transports amino acids within the cytoplasm to the ribosome. DNA Replication: Exact duplication of genetic material before cell division. Steps of Replication 1. Double stranded DNA unwinds and unzips between the weak bonds between the base pairs (The enzyme involved in replication is Helicase. 2. Each unzipped strand is a template, or pattern, for a new molecule of DNA to form (done by DNA Polymerase) 3. Free DNA nucleotides present in the nucleus bond to the exposed complimentary bases on the two DNA templates. This forms 2 new DOUBLE STRANDED DNA Molecules both identical to one another. ** Held together by WEAK Hydrogen Bonds**  Protein Synthesis Protein Synthesis: Making proteins DNA --> Protein --> Trait Codon: Three nucleotide sequences located on the mRNA sequence that codes specifically for an amino acid. Example: AGG/TAG/CGT/ATC Steps to synthesizing proteins... Part One - Transcription: Making of mRNA. The information in the DNA is transcribed (rewritten) to mRNA. ○​ The mRNA moves from the NUCLEUS to the CYTOPLASM ○​ It contains codons- 3 nucleotide sequence that codes for 1 amino acid Step One: The DNA template is used to make a single stranded RNA. RNA nucleotides base-pair with DNA nucleotides on the template strand. RNA has the base U which pairs with A in DNA. Step Two: mRNA leaves the nucleus. Part Two - Translation: The process by which the information coded for in the mRNA is used for the assembly of a particular amino acid sequence Step Three: mRNA and TRNA join the cytoplasm at the ribosome. Step Four: Amino Acids are carried to ribosome and joins according to the triplet code. Step Five: The protein is created. 1.​​ ​ ​ ​ 2. ​ ​ ​ ​ ​ 3.  Mutations Mutation: A sudden change in the structure or amount of genetic material ❏​ Most mutations are harmful ❏​ However some may be beneficial or have no effect Can be the raw materials to drive evolution ❏​ In order for a mutation to be inherited it must be present in the DNA of the gamete. ❏​ If a mutation occurs in a somatic cell (body cell) it can not be passed on to offspring. Mutagen: Any agent that causes a mutation at higher than spontaneous level. (Examples: Radiation, X-rays, UV rays, Radioactivity, Chemicals, Asbestos, Formaldehyde, Mustard Gas). 1. Gene Mutations: a mutation occurring in the sequence of bases. 2. Chromosomal Mutations: a mutation that occurs effecting a chromosome. A change in the NUMBER or STRUCTURE of Chromosomes in an Individual. Nondisjunction: Homologous chromosomes do not separate during meiosis. Down Syndrome: Trisomy 21 – Extra Chromosome #21. Polyploidy: Possession of extra sets of chromosomes.  Types of Chromosomal Mutations Translocation: "Relocate" Addition (Duplication): The addition of a piece of chromosome. Deletion: When a piece of a chromosome breaks off. Inversion: Reversing the order. Point Mutation: A mutation in which one nucleotide in a gene is changed Example: THE FAT CAT RAN FOR THE RAT Addition: THE GFA TCA TRA NFO RTH ERA T Deletion: THE ATC ATR ANF ORT HER AT  Genetics Technologies Cloning: Making an exact genetic copy of an organism How: –​Nucleus is removed from an egg cell of DONOR A –​Nucleus of body cell from DONOR B is inserted into DONOR A’s egg –​Egg cell is forced to divide using electricity = Embryo –​Embryo is placed in Uterus of DONOR C –​Baby is born. The baby is a clone of DONOR B because it has that donor’s DNA. Selective Breeding: Mating two organisms that have desired traits to produce one organism with both desired traits –​“Artificial Selection” How: –​Large Strawberries crossed with Sweet Strawberries –​Large, Sweet Strawberries are produced Recombinant DNA: Combining DNA from two different sources to produce the expression of a desired gene How: –​ Plasmid = circular bacterial DNA –​ Restriction Enzymes “cut” open the plasmid and cut out a desired gene from the human’s DNA –​ Other Enzymes “paste” the human gene into the DNA of the plasmid –​ The bacteria now starts producing the protein coded for in that gene. –​ When the bacteria reproduces (asexually), it will also make copies of the human gene. Gel Electrophoresis: Gel showing what different genes are present in a sequence of DNA based on the size of the gene Why: paternity tests, crime scenes, locating genes, comparing organisms How: –​ Restriction Enzymes cut the DNA at different locations –​ DNA (negative charge) is placed in a gel –​ Electricity (positive charge) is applied to the gel –​ DNA travels down the gel forming a unique pattern ​ Small/Light pieces travel far ​ Large/Heavy pieces don’t travel far