What are the steps in the scientific method?
(also - define hypothesis)
1- Define a problem.
2- Research the
problem.
3- Formulate a hypothesis
(a testable prediction – is may be thought of
as a possible explanation for a set of observations,
or an answer to a scientific questions.)
4- Design an experiment to test the hypothesis.
5- Make observations and record data. (If
observations involve numbers, they are quantitative,
otherwise they are qualitative.)
6- Analyze data and draw conclusion.
7- Publish the results.
Theory– A broad and comprehensive statement of what is believed to be true, that may tie together several related hypotheses.
It is supported by a large body of scientific evidence It can involve facts, scientific laws,
and tested hypotheses. It may result from continual verification and refinement of a hypothesis. As more information is gained, and new facts cannot be explained by present theories, those theories may be changed or replaced by new theories.
Many people use the word theory in their everyday language to mean a “guess.” When the word theory is used in science, it represents much more that just a guess.
Define experimental variables:
Variable – something that changes
Independent Variable – changed by the experimenter. An experiment can have only one.(manipulated)
Dependent Variable – it changes in response to the independent variable (responsive)-It changes because of what the experimenter changed while conducting the experiment
) Basic Biochemistry
hydrocarbons - are organic compounds of hydrogen and carbon such as carbohydrates.
carbohydrates – Carbo = carbon Hydrate = water
organic. compounds in which the ratio of H to C is 2:1.(sugars, starches and
cellulose) They are a primary energy source.
lipids- large, non polar, organic molecules that do not dissolve in H2O.(They have a higher ratio of C & H to O than carbohydrates.)
Lipid molecules (phospholipids) make up a large part of the cell membrane. Oils and fats are known as triglycerides. They store a lot of energy –more than bonds carbohydrates or protein.
saturated and unsaturated fats - fats with only single bonds between carbon atoms are saturated, while unsaturated fats have double and triple bonds, sometimes more than one.
proteins - composed mainly of C,H,O & N. Made up of building blocks called amino acids. They make up most structural components of cells and tissues. Enzymes are proteins. They differ in the kinds and amount of amino acids.
nucleic acids – (DNA & RNA) very large complex organic molecules that store genetic information. They are made up of nucleotides.
amino acids building blocks of protein (20 kinds,
those needed in the diet are called essential.
They are the protein monomers(“building-blocks”).
enzyme/substrate/lock & key – enzymes are organic, biological catalysts, that act on substrate molecules. There is a specific molecular fit between the enzyme and the substrate molecule – this is known as lock and key.
glucose/sucrose/fructose - glucose and fructose are monosaccharides also called
simple sugars. They are building blocks of carbohydrates. Glucose is an important energy source of cells. Sucrose, table sugar, is a disaccharide made up of glucose chemically bonded to fructose.
Condensation reaction – loss of H2O
Hydrolysis – add H2O to breakdown
mono/disaccharide/polysaccharides –
polysaccharide are made up of many simple sugar units (monosaccharides). Examples are cellulose and starch. They may be complex with branching chains. (A disaccharide is made up of two simple sugars. Ex: sucrose)
starch - storage form of glucose in plants (& algae). – make up the
complex carbohydrates.
glycogen –“animal starch” glucose storage(produced by liver, stored by liver & muscles)
cellulose - carbohydrate forms the cell wall of plant cells. –
provides a support structure and protection. It forms complex carbohydrates. Not digestible
in humans.
nucleotide – Pentose sugar + phosphate group + nitrogenous base = building block of DNA or RNA .
Classified by the type of nitrogenous base (Adenine A,
Guanine G, Cytosine C, Thymine T, and Uracil U)
enzyme– enzymes are proteins that act as catalysts.
ATP (Adenosine triphosphate) is the energy molecule of the cell. It is used by cells for all energy requiring activities.
Know your cellular organelles: What do they do?
nucleus -control center
mitochondrion - site of aerobic cell respiration
(Most ATP production)
nucleolus - aids in ribosome production
ribosome - protein production
lysosome - digestive enzymes
cell membrane - controls passage of materials in & out of the cell
chloroplast - site of photosynthesis
endoplasmic reticulum (rough & smooth) –movement of materials through the cell, it helps process proteins
centrioles – aids formation of the spindle during cell division (not found in plant cells)
Golgi apparatus – packages materials to be secreted from the cell
Cell wall – protects and supports the plant cell
Distinguish between prokaryotic and Eukaryotic cells: Prokaryotic - No nucleus or organelles
except ribosomes. Bacterial cells are prokaryotic. All other cells are eukaryotic.
Define the following terms related to movement of cellular materials:
passive transport - movement of material by that requires no energy from the cell. (diffusion, or osmosis) (Occurs with the concentration gradient)
active transport - movement of materials by the cell that requires cell energy (Often against the concentration gradient).
diffusion - random movement of materials from an area of greater to lesser concentration
osmosis - diffusion of water across a semi-permeable membrane
hypertonic – has more solutes that in the cell, and therefore it has less water (water moves out of the cell)
hypotonic solution - has less solutes than in the cell, and therefore it has more water (water moves into the cell)
isotonic solution – - has the same solutes as inside the cell and therefore the same amount of water. (No net movement of water)
plasmolysis - plant cells in hypertonic solution (content shrivel)
concentration gradient – unequal amounts of a substance across a given area. It must be present for diffusion to occur.
Know your energy transfer in the biosphere: Define & give examples of energy pyramid & trophic levels.
Trophic level
= how an
organism
obtains its
nutrition
Distinguish between food chains, & food webs. (Be able to identify producers, 1st order (primary) consumers, 2nd order consumers, etc.)
Food Chain – a series of steps in an ecosystem, through which organisms transfer energy by eating or being eaten.
Food Web – interconnected food chains in an ecosystem (it demonstrates more complex feeding relationships).
An autotrophic organism that captures energy to make organic molecules(examples: plants, algae, some bacteria)
heterotroph – an organism that obtains organic food molecules by eating other organisms or their byproducts.
decomposer – an organism that obtains organic nutrients from dead organic matter
How much energy is transferred from one trophic level to the next? only 10% - 90% not captured!
biosphere – the area on, or around earth where all life exists (land, water, air)
biome – a group of ecosystems that have the same climate and dominant communities (has specific vegetation and other characteristics
biomass – the dry weight of organic material in an ecosystem.
biotic factor – the living component of the ecosystem
abiotic factor – a nonliving component of an ecosystem (such as: climate, rainfall, soil composition, temperature etc.)
Distinguish between the carbon and water cycles
Carbon Cycle: Cycling between organic and inorganic forms of carbon – such as between CO2 and glucose (C6H12O6) Atmosphere – Inorganic Carbon. (Nitrogen cycle – between inorganic nitrogen
gas in the atmosphere and organic nitrogen needed by plants)
THE WATER CYCLE Water moves between the ocean atmosphere, and land. Water molecules enter the atmosphere as water vapor, a gas that from bodies of water.
The process of water changing from liquid to atmospheric gas is called evaporation. It can also enter the atmosphere from the leaves of plants in aprocess called transpiration.
Eventually, the water vapor forms tiny droplets that form clouds. This is known as condensation.
precipitation–rain, snow, sleet, or hail.
) In the carbon cycle, what organelle “makes food” out of CO2 and H20. – Photosynthesis (Chloroplast – fixes carbon in the Calvin cycle) CO2 given off from animals during cell respiration.
What is global warming? What may cause it?
Greenhouse gases trap heat (such as man made CO2 emissions from fossil fuels.)
Distinguish between a habitat & niche. habitat -It is the physical area or
the place, in which an organism lives. (a forest, a pond, a lake etc.)
niche It is the organism’s way of life, or the role the species plays in its environment.
(all its interactions in the environment.)
What are the products and reactants in photosynthesis and cell respiration:
Photosynthesis: (in chloroplast of plant cells)
6CO2+ 6 H2O Light C6H12O6 + 6O2
carbon water glucose oxygen
dioxide
----reactants------products---
Cell respiration: (in cytoplasm & mitochondrion of plant & animal cells)
C6H12O6 + 6O2 6CO2 + 6 H2O
glucose oxygen carbon dioxide water
----reactants------products---
Distinguish between light reactions, Calvin cycle, C-4 photosynthesis: What are some C-4 plants? Light reations occur in the stroma of the chloroplast. Photosystem I & II absorb light energy, electrons move through electron transport proteins, water splits, O2 is given off, ATP and NADPH is produced for the Calvin cycle. In the Calvin cycle –which occurs in the stroma,
inorgnaic carbon is converted to organic carbon in the form of PGAL. (Glucose is produced)
Some plants, adapted to hot, dry environments, use a special
process called C4 photosynthesis. Examples of these plants are : Corn, Sugar Cane
Crabgrass and most tropical grasses are C4 plants. Plants that only use the Calvin cycle for light
independent reactions may be referred to as C3 because the 6-C sugar splits to two 3-carbon sugars. In C-4 photosynthesis. Carbon dioxide is first incorporated into a C-4 (four carbon) acid in the mesophyll cells.
CAM Photosynthesis Crassulacean Acid Metabolism (an organic acid) It is a specialization discovered in desert plants such as cactus and pineapple. CAM evolved in plants that grow in extreme heat & little rain. (It is not very efficient, and plants grow slowly.) CAM plants can open their stomata at night. They incorporate CO2 into organic acids within cell vacuoles.
Label the stages of mitosis & briefly describe what happen in each.
Define the concepts of cell division:
mitosis - cell division produces diploid cells
(two daughter cells)
meiosis (reduction division) cell division
produces haploid gametes (crossing-over in
prophase I increases genetic variation)
haploid - N chromosomes # (humans = 23)
diploid – 2N chromosome # (humans = 46)
gamete - sex cell (sperm, pollen grain or egg cell
pollen – a plant’s male gamete
zygote – sperm and egg cells fuse to form a zygote during fertilization
cell plate – divides plant cells during cytokinesis
cleavage furrow –divides animal cells during cytokinesis
Know your DNA & Protein Synthesis:
DNA/tRNA, mRNA, rRNA, codon, anticodon.
DNA – nucleic acid – genes, chromosomes are composed of DNA - carries the hereditary information. It is located in the nucleus. Transciption of DNA produces RNA. mRNA (messenger RNA) which leaves the nucleus with the DNA code for protein construction. mRNA travels to the ribosome which contains rRNA (ribosomal RNA). The tRNA (transfer RNA) brings the amino acids to the proper place in the growing protein. The “codon” of mRNA bonds to the “anticodon” of tRNA.
Replication, transcription, translation – Replication is the process of
duplicating DNA (during S phase of cell cycle.) transcription is the process of producing RNA,while translation is the process of producing a protein which involves all forms of RNA as mentioned above.
helicases, polymerases - helicases are enzymes that break the H bonds between the bases of
DNA to “unzip” the two DNA strands. Polymerases are enzymes that bond the DNA or RNA
nucleotides and take part in the corrective editing process.
Solve the following Punnett square crosses (include genotypic and phenotypic ratios in your examples): Monohybrid pea plant – complete dominance
18) TT x tt (P1) Mendel crossed tall & short pure bred plants
19) Tt x Tt (F1)
Mendel’s Principles: Dominance, Segregation, Independent Assortment
Know your genetics terms:
dominant - allele that masks the recessive & expressed its phenotype
recessive - allele that is masked by the dominant alleles Gregor Mendel and is only expressed in the homozygous genotype(tt)
phenotype -physical expression of the genes(short pea plant)
genotype - alleles that are present (Tt, TT or tt)
homozygous - two of the same alleles(TT or tt)
heterozygous - two different alleles (Tt)
sex-linked – genes for the trait are located on a sex chromosome
Sex-influenced – alleles on the autosomes,
but phenotype is influenced by person’s gender (male pattern baldness)
Incomplete dominance – in the heterozygous genotype, both alleles cause a “blending” of phenotypes to create a third phenotype (White and red = pink flowers)
Codominance – two phenotypes expressed at the same time
(white hairs & red hairs= roan cattle)
Chromosome disorders: CAUSED BY NONDISJUNCTION
Down’s syndrome (“trisomy 21” an autosomal chromosome disorder) - There is an extra chromosome at pair 21 (trisomy) This results in characteristic facial features, mental retardation, possible respiratory or heart problems, small stature etc.-
XO – Turner’s Syndrome (sex chromosome disorder) It is a form of monosomy. A women missing an X chromosome.