What is science?
Science is an intellecual activity, encompassing observation, description, experimentation and explanation of natural phenomena.
Is a scientist supposed to be skeptic?
Yes, a good scientist is supposed to be skeptical, a disbeliever at heart, to a point.
What is superstition?
Superstitions are the irrational belief that actions that are not logically related to a course of events can influence its outcome.
The scientific method is defined by our author as "the process of...
The scientific method is defined by our author as "the process of examination and discovery.
Empirical knowledge is based on observations that are...
Empirical knowledge is based on experience and observations that are rational, testable and repeatable.
What are the 5 basic steps of the scientific method?
- 1 )Make observations
- 2) formulate a hypothesis
- 3) devise a testable prediction
- 4) conduct a critical experiment
- 5) draw conclusions and make revisions
What is it about the scientific method that keeps a scientist honest?
Scientists are kept honest by having others perform their experiment.
What is a hypothesis, and what is a null hypothesis and why is it easier to disprove?
A hypothesis is a proposed explanation for observed phenomena. A null hypothesis is a hypothesis that states a lack of relationship between two factors. It is easier to disprove because a single piece of evidence or single new obeservation that contradicts a null hypothesis is sufficient to reject it.
If an experimental result is not what you expected, that does not make it a ______ answer.
If an experimental result is not what expected, that does not make it a"wrong answer"
What is the difference between a hypothesis and a theory?
A hypothesis is a proposed explanation of a phenomena A theory is a hypothesis that has withstood the test of time and is unlikely to be altered by new eveidence. Both are still testable, however the theory has already been repeatedly tested and no observation of experimental results have contradicted it.
What is a the placebo effect?
The placebo effect is when people respond favorably to any treatment regardless of the type of treatment. We do not fully understand why this works we just know it happens.
What is a double blind test?
A double blind test is when both the experimental subjects and the experimenter do not know who is receiving the actual treatment.
Why must a study be reproduceable and repeatable?
Repeating a n experiment is the only way to keep scientists honest.
What is statistics, and why are they used in science?
Statistics is a set of analytical and mathematical tools designed to help researchers gain understanding from the data they gather, which then leads to greater degree of confidence.
Can science do everything and answer every question?
No there are limits to what science can do. It does not generate moral statements and cannot give insight to ethical problems.
What is hierarchiacal organization?
Life is organized into hierarchical levels, such as atoms, cells, tissues, organs, organisms, populations, communities, ecosytems and biospehere.
Define a Cell.
The cell is the basic unit of an organism, the smallest unit of life that can function independently and perform all the necessary functions of life, including reproducing itself.
Who was the first person to use the term cell?
Robert Hooke, a British scientist, coined the term (small room) while viewing a thin piece of cork.
What is the cell theory?
The cell theory states that (1) all living organism are made up of one or more cells, (2) all cells arise from other, pre-existing cells.
What is a prokaryotic cell?
Prokaryotic cells do not possess a nucleus; its DNA simply resides in the middle of the cell.
How long ago did prokaryotic cells appear?
They appeared 3.5 billion years ago.
What are the 4 basic structures of a prokaryotic cell?
- (1) a plasma membrane
- (2) a cytoplasm
- (3) ribosomes
- (4) one circular loop or linear strand of DNA
What is a eukaryotic cell?
Eucaryotic cells have a nucleus which contains linear strands of DNA, and they usually contain specialized structures called organelles.
How long ago did eukaryotic cells appear?
They appeared 2 billion years ago.
What is the endosymbosis theory?
- Endosymbiosis theory is the idea that chloroplasts and mitochondria are actually bacteria. Obsrevations that support this are that chloroplasts and mitochondria..
- (1) are like small bacteria
- (2) have DNA in a loop like bacteria
- (3) divide by fission like bacteria
- (4) have bacterial ribosomes
How is a plasma membrane the gate keeper of a cell?
The plasma membrane acts like a gate keeper by controlling the flow of molecules into and out of the cell.
What is a phospholipids, and how are they arranged in membranes?
- A phospholipid has a head consisting of a glycerol and phosphorous and is ploarized, and two tails (fatty acids) that are non-polarized.
- They are arranged in a double layer with the tails pointing to one another, and the heads of one layer facing the interior of the cell, while the other is facing the exterior of the cell.
What is hydrophobic and hydrophilic?
What other molecules can be found floating among the phospholipids?
Various proteins are also found floating among phospholipids.
Name the four primary types of membrane proteins
- 4 primary types of membrane proteins
- (1) receptor proteins-bind chemical in the cells external enviornment.
- (2) recognition proteins-gives the cell a fingerprint.
- (3) transport proteins-help large and polar molecules through.
- (4) enzymes-accerlerate chemical reactions on the membrane.
What is the function of cholesterol in a cell membrane?
Cholseterol, a lipid, helps the membrane maintain its flexibility/
What is passive transport?
Passive transport is the movement of substances across the membrane without the input of energy.
What is simple diffusion?
Simple diffusion is the movement of substances from an area of higher concentration to an area of lower concentration through the membrane.
What is facilitated diffusion?
Facilitated diffusion is for bigger molecules who cannot get through the phospholipids bilayer. This requires a transport protein.
What is osmosis.
Osmosis is the simple diffusion (passive transport) of water across a membrane from an area of higher concentration of water to an area of lower concentration of water.
Differentiate between hypertonic, hypotonic and isotonic solutions.
- hypertonic solution- Higher concentration of solute than a cell.
- hypotonic solution- has less solute than the cell and therefore a higher concentration of water.
- isotonic solution- solution has the same solute concentration, and therefore the same water concentration.
What is active transport?
Active transport is the movement of a substance into or out of the cell that goes against the concentration gradient (low to high), and requires an expenditure of energy.
Explain endocytosis and ecotysosis.
- endocytosis-cells engulfing any large particle.
- exocytosis- pouring out large particles from the cell.
Explain phagocytosis and pinocytosis?
- Phagocytosis-is a special endocytosis where white blood cells engulf pathogens (like amoeba eating something)
- Pinocytosis- is a endocytosis where cells drink dissolved substance.
Name two functions of the nucleus?
- (1) directing most of the cellular activities by controlling which molecules are produced.
- (2) is the storehouse for hereditary information.
What are the three important structural components in the nucleus?
- 3 Important Structural Components of Nucleus
- (1) a double bilayer nuclear membrane with pores.
- (2) possesion of chromatin (uncoiled DNA).
- (3) a nucleolus which the subunits of ribosomes are made.
What is the cyto skeleton?
The inner scaffolding of the cells is the cytoskeleton. It gives the cell shape and support, controls the intercellular traffic flow, and since it can generate force, it gives all cells some ability to control their enviornment.
What are cilia?
Cilia are short projections that often occur in large numbers on a single cell, and beat swiftly in unison. They move fluid past a cell. (Flagella are much longer than cilia)
What is mitochondrion?
Mitochondria are the cells all-purpose energy converters. They convert food energy into ATP energy. (It consists of two membranes, an outer and inner that forms folds) It also contains DNA and ribosomes.
What is a lysosome?
Lysosomes are round, membrane-enclosed, acid-filled vesicles that function as garbage disposals. (One specific function is that they can break down pathogens)
What is the endomembrane system?
Central to the endomembrane system is the endoplasmic reticulum which produces and modifies biological molecules. The rough endoplasmic reticulum produces proteins, while the smooth endoplasmic reticulum manufactures fats. It also gives rise to Golgi apparartus, and lysosomes, if required , to more nuclear and cell membranes.
What is the Golgi apparatus?
The Golgi apparatus process molecules synthesized in the cell and packages them for transport elsewhere.
What is the cell wall?
The cell wall is a stucture that surrond the cell membrane of plants. It is made form polysaccharide called cellulose, and confers structural strength to the cell.
What is a central vacuole?
The central vacuole is a membrane bound organelle of plants that occupies 50 to 90% of its interior space. (The vacuole stores nutrients, uses it like a lysosome to degrade materials, may contain poisons to deter predators, contains pigments to attract pollinators. and through turgor pressure provides physical support)
What is a chloroplast?
The chloroplast is the green, double membrane organelle of a plant cell. (Specifically this is the location of photosynthesis and the production of food and free Oxygen)
What is the difference between an atom and an element?
An element is a substance that cannot be broken down chemically into any other substances. An atom is the smallest part of any element.
Name three subatomic particles of an atom
- At center of atom is a nucleus made up of protons and neutrons
- protons-are particles that have a positive electric charge
- neutrons-are particles that have no electrical charge. Spinning around the nucleus are negatively charged particles called electrons. (electrons are so small they virtually have no mass)
Why don't electrons collapse into the nucleus?
The attraction of the electrons in orbits to the protons in the nucleus is enough to keep the electrons from flying away, and the energy of the electrons fast movement keeps them from collapsing into the nucleus.
Atoms of different elements have different numbers of ______, which distinguish one element from another element.
Atoms of different elements have different numbers of protons, which distinguish one element from another element.
How many natural occurring elements have been found on the earth?
90 naturally occurring elements have been found on the earth.
What specific particle of an atom determines how it bonds with other atoms?
Electrons determine how the atom will bond.
How does an atom become stable or non-reactive?
Atoms become stable or non-reactive when their outermost shell of electrons is filled to capacity.
What is an electron shell?
Electrons move around designated areas called electron shells. An atom can have as many as 7 electron shells in total-it simply depends on how many electrons it has to fill them up.
What is an ion?
An ion is a positive or negative charged atom.
Where do molecules store energy?
Molecules store energy in the bonds between atoms.
What is a covalent bond?
A covalent bond is between two or more atoms where the atoms are sharing their electrons. ( Carbon can form four covalent bonds)
What is an ionic bond?
In an ionic bond, one atom transfers one or more of its electrons completely to another. As a result of this each atom becomes an ion of opposite charge, and they attract one another and bond.
What is a hydrogen bond?
A hydrogen bond is formed between a hydrogen atom in one molecule another atom in another molecule.
What is the difference between a molecule and a compound?
- A molecule is a group of atoms that are held together by covalent bonds.
- Compounds are formed between two different atoms ionically.
What is a polar molecule?
A polar molecule is a molecule with charge-one side is positive and the other side is negative. This is a result of unequal sharing of electrons.
What is it about a molecule that determines its properties?
The shape of a molecule determines its properties.
The cohesiveness of water is due to _____ bonds.
The cohesiveness of water is due to hydrogen bonds.
Does water change its temperature easily?
No, water does not easily change its temperature. In fact, it resist temperature change.
Which is less dense, solid water or liquid water?
Solid water (ice) is less dense because when liquid water freezes the hydrogen bonds arrange water molecules into a crystallin lattice keeping them slightly apart and therefore less dense.
What do acidic solutions realease?
Acidic solutions release hydrogen ions (H+)
What do basic solutions release?
Basic solutions release hydoxyl ions (-OH)
What kind of chemicals act to maintain a stable pH?
Buffers are chemicals that act to maintain a stable pH.
What is a macromolecule? Name the 4 types?
- A macromolecule is a large molecule that is made up from smaller building blocks or subunits (monomers)
- 4 kinds of macromolecules
- (1) Carbohydrates
- (2) Lipids\
- (3) Proteins
- (4) Nucleic acids
What is the basic function of carbohydrates?
The basic function of carbohydrates is to act as energy sources.
What is a monnosaccharide?
A monnosaccharide is a simple sugar like glucose or fructose.
What are the 3 fates of glucose in your blood?
- The three fates of glucose in your blood
- (1) fuel for cellular activity
- (2) stored temporarily as glycogen in the liver
- (3) conversion to fat
What is polysaccharide?
A polysaccharide is a complex carbohydrate-more than one sugar(sometimes 10,000 sugars linked together). Cellulose is found in all plant cell walls.