In the following data table of an experiment carried out at 4° C (39.2° F) over 4 hours, which of the following options represents the dependent variable? Solution in bag Solution outside bag Bag mass change (g) water water   -0.2 20% sucrose   water   +2.4   40% sucrose   water   +4.3   60% sucrose   water   +5.8  

A. Duration

B. Temperature

C. Sucrose concentrations

D. Bag mass change

Answer Explanation:

The dependent variable is the variable that is measured or observed in an experiment. It is the variable that changes as a result of the independent variable, which is the variable that is manipulated or controlled by the experimenter. In this case, the dependent variable is the bag mass change, because it depends on the sucrose concentrations in the bag and outside the bag. The other variables, such as duration, temperature, and sucrose concentrations, are independent variables that are set by the experimenter.

Therefore, the Correct Answer is D.

Q #1: Which of the following ions binds to the troponin complex, initiating contraction of a muscle?

A. Sodium

B. Potassium

C. Calcium

D. Phosphorus

Answer Explanation

When a muscle cell is stimulated by a nerve impulse, calcium ions are released from the sarcoplasmic reticulum into the cytoplasm. The calcium ions bind to the troponin complex, which is a protein that regulates the interaction between actin and myosin filaments. The binding of calcium to troponin causes a conformational change that exposes the binding sites for myosin on the actin filaments. This allows the myosin heads to attach to the actin and pull the filaments past each other, resulting in muscle contraction.
Q #2: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?

A. Osmosis

B. Diffusion

C. Facilitated diffusion

D. Active transport

Answer Explanation

One of the ways that cells regulate their water balance is by adjusting to different solute concentrations in their environment. When a cell is placed in a solution that has a higher concentration of solutes than the cell itself, the solution is called hypertonic. In this case, water will tend to move out of the cell through special channels called aquaporins, which are embedded in the plasma membrane. This movement of water across a selectively permeable membrane is a type of passive transport called osmosis. Osmosis does not require any energy input from the cell, unlike other forms of transport such as diffusion, facilitated diffusion, or active transport.
Q #3: Nitrogen gas is an extremely stable molecule because its structure contains which of the following?

A. lonic bonds

B. Triple covalent bonds

C. Resonance bonds

D. Hydrogen bonds

Answer Explanation

Triple covalent bonds. Nitrogen gas consists of two nitrogen atoms that share three pairs of electrons, forming a triple bond. This bond is very strong and requires a lot of energy to break. Ionic bonds, resonance bonds, and hydrogen bonds are weaker types of bonds that do not occur in nitrogen gas.

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More Questions on TEAS 7 Science

Q #1: Which of the following ions binds to the troponin complex, initiating contraction of a muscle?

Answer Explanation

Q #2: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?

Answer Explanation

Q #3: Nitrogen gas is an extremely stable molecule because its structure contains which of the following?

Answer Explanation

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