Biology Midterm Review Essay
Biology Midterm Review
1.1
• The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful prediction
• Scientific thinking usually begins with observation, the process of gathering information about events or processes in a careful
-observation generally involves using the senses esp. hearing & sight
-the information gathered from observations is called data.
• Quantitative date expressed as number
-Qualitative data are descriptive and involve characteristics
• After observations, the researchers will propose one or more hypotheses.
• A hypothesis- is a proposed scientific explanation for a set of observation
-some hypotheses are tested …show more content…
by gathering more data
1.2
• Spontaneous generation- hypothesis stating that life could arise from nonliving matter
• Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled.
• Controlled experiment-a test of the effect of a single variable by changing it while keeping all other variables the same.
• Manipulated variable- factor in an experiment that a scientist purposely changes (INDEPENDENT VARIABLE)
• Responding variable- factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable (DEPENDENT VARIABLE)
• Theory- well-tested explanation that unifies a broad range of observation
1.3
• Living things share some characteristic
-living things are made up of units called cells
-living things reproduce
-living things are based on a universal genetic code
-living things grow and develop
-living things obtain and use materials and energy
-living things respond to their environment
-living things maintain a stable internal environment
-taken as a group, living things change over time
• Some of the levels at which life can be studied include molecules, cells, organisms, populations of a single kind of organism, communities of different organisms in an area, and the biosphere. At all these levels, smaller living systems are found within larger system
• Levels of Organization
-Biosphere (largest & most complex)
-Ecosystem
-Community
-Population
-Organism
-Groups of Cells
-Cells
-Molecules (smallest, that make up living things)
1.4
• Most scientists use the metric system when collecting data and performing experiments
• Metric system- a decimal system of measurement whose units are based on certain physical standards & are scaled on multiples of 10
• Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eyes
• Light microscopes produce magnified images by focusing visible light rays.
Electron microscopes produce magnified images by focusing beams of electrons.
-most commonly used microscope
• Compound light microscopes – allow light to pass through the specimen and use two lenses to form an image.
• Electron microscope- use beams of electrons, rather than light, to produce images.
• Transmission electron microscope (TEMs) shine a beam of electrons through a thin specimen.
• Scanning electron microscopes (SEMs) scan a narrow beam of electrons back and forth across the surface of a specimen.
2.1
•
• Most elements are found combined with other elements in compound.
• A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions.
• The main types of chemical bonds are ionic bonds and covalent bonds
• An ionic is formed when one or more electrons are transferred from one atom to another
-an atom that loses electrons has a positive charge.
-an atom that gains electrons has a negative charge
• These positively and negatively charged atoms are known as ions
• A covalent bond- forms when electrons are shared between atoms.
-when the atoms share two electrons, the bond is called a single covalent
bond
• When atoms are joined together by covalent bonds is called molecule
• The molecule is the smallest unit of most compounds
2.2
• Water is neutral. It is polar. Water is not always pure it is often found as part of a mixture.
• A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms
• The attraction between the hydrogen atom on one water molecule & the oxygen atom on another water molecule is an ex: of a hydrogen bond
• Cohesion- is an attraction between molecules of the same substance
-water is extremely cohesive
• Adhesion- is an attraction between molecule of different substances
• Mixture- is a material composed of two or more elements or compounds that are physically mixed together but not chemically combined
• All of the components of a solution are evenly distributed throughout the solution
• Solute the substance that is dissolved ex: Table salt
• Solvent- the substance in which the solute dissolve. Ex: Water
• Suspension- mixture of water and nondissolved material
• Chemists devised a measurement system called pH scale to indicate the concentration of H+ ions in solution
-0 to 6/6.5 is acidic
-7 is neutral
-7.5/8 to 14 is basic
2.3
1.1
• The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful prediction
• Scientific thinking usually begins with observation, the process of gathering information about events or processes in a careful
-observation generally involves using the senses esp. hearing & sight
-the information gathered from observations is called data.
• Quantitative date expressed as number
-Qualitative data are descriptive and involve characteristics
• After observations, the researchers will propose one or more hypotheses.
• A hypothesis- is a proposed scientific explanation for a set of observation
-some hypotheses are tested …show more content…
by gathering more data
1.2
• Spontaneous generation- hypothesis stating that life could arise from nonliving matter
• Whenever possible, a hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled.
• Controlled experiment-a test of the effect of a single variable by changing it while keeping all other variables the same.
• Manipulated variable- factor in an experiment that a scientist purposely changes (INDEPENDENT VARIABLE)
• Responding variable- factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable (DEPENDENT VARIABLE)
• Theory- well-tested explanation that unifies a broad range of observation
1.3
• Living things share some characteristic
-living things are made up of units called cells
-living things reproduce
-living things are based on a universal genetic code
-living things grow and develop
-living things obtain and use materials and energy
-living things respond to their environment
-living things maintain a stable internal environment
-taken as a group, living things change over time
• Some of the levels at which life can be studied include molecules, cells, organisms, populations of a single kind of organism, communities of different organisms in an area, and the biosphere. At all these levels, smaller living systems are found within larger system
• Levels of Organization
-Biosphere (largest & most complex)
-Ecosystem
-Community
-Population
-Organism
-Groups of Cells
-Cells
-Molecules (smallest, that make up living things)
1.4
• Most scientists use the metric system when collecting data and performing experiments
• Metric system- a decimal system of measurement whose units are based on certain physical standards & are scaled on multiples of 10
• Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eyes
• Light microscopes produce magnified images by focusing visible light rays.
Electron microscopes produce magnified images by focusing beams of electrons.
-most commonly used microscope
• Compound light microscopes – allow light to pass through the specimen and use two lenses to form an image.
• Electron microscope- use beams of electrons, rather than light, to produce images.
• Transmission electron microscope (TEMs) shine a beam of electrons through a thin specimen.
• Scanning electron microscopes (SEMs) scan a narrow beam of electrons back and forth across the surface of a specimen.
2.1
•
• Most elements are found combined with other elements in compound.
• A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions.
• The main types of chemical bonds are ionic bonds and covalent bonds
• An ionic is formed when one or more electrons are transferred from one atom to another
-an atom that loses electrons has a positive charge.
-an atom that gains electrons has a negative charge
• These positively and negatively charged atoms are known as ions
• A covalent bond- forms when electrons are shared between atoms.
-when the atoms share two electrons, the bond is called a single covalent
bond
• When atoms are joined together by covalent bonds is called molecule
• The molecule is the smallest unit of most compounds
2.2
• Water is neutral. It is polar. Water is not always pure it is often found as part of a mixture.
• A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms
• The attraction between the hydrogen atom on one water molecule & the oxygen atom on another water molecule is an ex: of a hydrogen bond
• Cohesion- is an attraction between molecules of the same substance
-water is extremely cohesive
• Adhesion- is an attraction between molecule of different substances
• Mixture- is a material composed of two or more elements or compounds that are physically mixed together but not chemically combined
• All of the components of a solution are evenly distributed throughout the solution
• Solute the substance that is dissolved ex: Table salt
• Solvent- the substance in which the solute dissolve. Ex: Water
• Suspension- mixture of water and nondissolved material
• Chemists devised a measurement system called pH scale to indicate the concentration of H+ ions in solution
-0 to 6/6.5 is acidic
-7 is neutral
-7.5/8 to 14 is basic
2.3