Honors Biology Exam Review

A controlled experiment is a scientific study that aims to isolate and test the effect of a specific factor (independent variable) on a measurable outcome (dependent variable). It involves comparing the results of an experimental group, where the independent variable is manipulated, to a control group, where the independent variable remains constant. Other factors (standardized variables) are kept the same across both groups to ensure that any observed difference is due to the independent variable.

A hypothesis is a testable prediction or proposed explanation for an observation or phenomenon. It's a 'educated guess' about the relationship between variables, formed based on prior knowledge and observations.

The independent variable is the factor that a scientist intentionally changes or manipulates in an experiment. It's the 'cause' in a cause-and-effect relationship.

The dependent variable is the factor that is measured or observed in an experiment. It's the 'effect' in a cause-and-effect relationship. It's what happens as a result of the changes made to the independent variable.

Standardized variables (also called controlled variables) are factors that are kept constant throughout an experiment. They are important because they help ensure that any observed change in the dependent variable is due to the independent variable, not to other uncontrolled factors.

A control group in an experiment serves as a baseline for comparison. It is treated exactly like the experimental group, except for the independent variable, which is not manipulated in the control group. This allows scientists to determine whether the observed changes in the experimental group are directly caused by the independent variable.

A scientific theory is a well-substantiated explanation of some aspect of the natural world that is supported by a large body of evidence and has been repeatedly tested and confirmed through observation and experimentation. It is a highly reliable explanation that has been rigorously tested and is widely accepted within the scientific community.

Replication is the process of repeating an experiment multiple times, often with different subjects or under different conditions. This helps to determine the reliability and validity of the results, ensuring that the findings are not due to random chance or errors.

DNA is housed in a region called the nucleoid, which is not membrane-bound.

Eukaryotic cells have DNA enclosed within a membrane-bound nucleus.

Prokaryotic cells typically lack membrane-bound organelles, while eukaryotic cells have many.

The hydrophobic tails of phospholipids face inwards, creating a barrier, while the hydrophilic heads interact with the watery environment.

The cell membrane is selectively permeable, meaning only certain molecules can pass through it.

Passive transport does not require energy (ATP) and relies on the concentration gradient to move molecules.

Diffusion is the movement of molecules from an area of high concentration to low concentration.

Osmosis is the diffusion of water across a selectively permeable membrane from high water concentration to low water concentration.

Facilitated diffusion uses transmembrane proteins to help move molecules down the concentration gradient.

A concentration gradient is the difference in concentration of a substance across a membrane.

Down the concentration gradient means moving from a region of high concentration to low concentration.

Against the concentration gradient means moving from a region of low concentration to high concentration.

In an isotonic solution, the water concentration inside and outside the cell is the same.

In a hypertonic solution, the water concentration outside the cell is lower than inside the cell, causing water to move out of the cell.

In a hypotonic solution, the water concentration outside the cell is higher than inside the cell, causing water to move into the cell.

A set of chemical reactions that occur within a cell to sustain life.

Changes in the genetic makeup of a population over time.

A change in the DNA sequence.

The process of copying DNA to create new DNA molecules.

The process of copying a gene's DNA sequence into RNA.

The process of using RNA to create proteins.

The process of proteins carrying out their functions and influencing traits.

A theoretical diagram representing a possible sequence of how species evolved on Earth, showing the evolutionary relationships between organisms.

A bond where electrons are shared unequally, with one atom having a partial negative charge and the other a partial positive charge.

It has a partially positive side (hydrogen) and a partially negative side (oxygen) due to the unequal sharing of electrons in the covalent bond.

Attractive forces between the partially positive hydrogen of one water molecule and the partially negative oxygen of another water molecule.

Carbon can form four bonds with other atoms, including other carbons, leading to a wide variety of structures and functions.

Twenty different amino acids.

The 'R' group, or side chain, makes each amino acid unique.

Nucleotides, composed of a sugar, a phosphate, and a nitrogenous base.

Levels of treatment are the different values or groups of the independent variable that are tested. It creates the experimental groups.

Controlled variables are factors that are not directly manipulated, but they are kept consistent as much as possible throughout the experiment. They are not the focus of the study, but they could potentially impact the results.

The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. It applies to living organisms since they must obtain energy from their environment as chemical energy, which is then converted into other forms of energy for cellular processes.

The second law of thermodynamics states that entropy, a measure of disorder or randomness, always increases within a closed system. Living things are highly ordered and seem to violate the second law of thermodynamics. However, they do not because they are constantly taking in organized molecules from their environment and releasing less ordered molecules as waste, maintaining a constant order within themselves. Eventually, decomposition and decay will return them to the environment, which will increase entropy.

Entropy is a measure of disorder or randomness within a system. The higher the entropy, the more disordered the system. Because organisms are highly ordered, they must constantly take in energy to maintain their ordered state. They release heat and waste products, increasing the entropy of their surroundings as they consume organized energy from their environment.

A cell is considered the simplest biological entity because it is the smallest unit of life that can carry out all the life processes. It is self-contained and can reproduce, grow, and develop independently. It is able to obtain and transform energy for its processes, interact with the environment, and maintain its own internal environment.

The structure of a phospholipid consists of a hydrophilic head (phosphate and glycerol) and two hydrophobic tails (fatty acid chains). When in water, the hydrophobic tails aggregate together to minimize contact with the water while the hydrophilic heads face the water.

The central dogma of molecular biology describes the flow of genetic information within a biological system. It describes how DNA is transcribed into RNA, which is then translated into proteins. These proteins are responsible for carrying out the essential functions of the cell.

The organelle responsible for containing and replicating genetic material, as well as producing RNA.

A double phospholipid bilayer perforated with nuclear pores that encloses the nucleus.

A network of membranes involved in the synthesis and transport of molecules, consisting of rough and smooth ER.

The internal compartment of the ER where synthesis takes place, such as protein synthesis.

ER studded with ribosomes, responsible for protein synthesis.

ER without ribosomes, responsible for lipid and carbohydrate synthesis.

A stack of flattened membranes responsible for modifying and packaging new molecules.

Small membrane-bound sacs that transport materials between the ER, Golgi, and other parts of the cell.

An organelle covered with a phospholipid bilayer that contains enzymes for breaking down waste materials.

The idea that mitochondria and chloroplasts were once free-living prokaryotes that were engulfed by a larger cell.

The basic building block of DNA, composed of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

The sequence of nucleotides in DNA that carries genetic information.

The two strands of a DNA molecule run in opposite directions (5' to 3' and 3' to 5').

The two strands in the DNA double helix run in opposite directions due to their polarity.