B4B

The diagram below shows how a paramecium maintains homeostasis. A paramecium normally lives in a hypotonic environment in which water continually diffuses into the cell. To maintain homeostasis, the paramecium must pump out large amounts of water using its contractile vacuole.

If the paramecium is then places in a hypertonic environment, which of the following will occur?

• water will diffuse into the paramecium

• water will diffuse out of the paramecium

• salt will be pumped out of the paramecium by the vacuole

• salt will be pumped into the paramecium by the vacuole

Which of these statements best explains the process of energy conversion that takes place in the mitochondria?

• energy is required for carbon dioxide molecules to form six-carbon sugar molecules

• water molecules and radiant energy are necessary for anaerobic respiration to take place

• oxygen molecules release energy in the form of heat during combustion reactions

• the energy in the bonds of glucose molecules is transferred to the phosphate bonds in ATP

Which cellular process takes place in the ribosomes that are bound to the endoplasmic reticulum?

• the breakdown of waste material

• the conversion of radiant energy to glucose

• the synthesis of new proteins

• the replication of nucleic acide

Which group of organelles is directly responsible for the production of new molecules within a cell?

• Ribosomes, the endoplasmic reticulum, and Golgi apparatuses

• Golgi apparatuses, lysosomes, and the plasma membrane

• The endoplasmic reticulum, plastids, and vacuoles

• The nucleolus, vacuoles, and ribosomes

The cellular process known as a sodium-potassium pump was discovered in the 1950's by Jens Christian Skou, a Danish scientist. This process is a form of active transport that moves three sodium ions to the outside of a cell for every two potassium ions that it moves into the cell. Which of these best explains why energy is needed for active transport?

• Ions are negatively charged

• Ions are attached to large proteins

• Ions are trapped inside the plasma membrane

• Ions are moved against the concentration gradient.

Cells can generate as many as 36 - 38 molecules of adenosine triphosphate (ATP) from the metabolism of one molecule of glucose. Which cellular process results in this amount of ATP production

• Anaerobic cellular respiration

• Protein synthesis

• Aerobic cellular respirtaion

• Photosynthesis

Some students used vinegar to dissolve away the shells of three eggs and used these eggs as models of human red blood cells. The students observed the changes in the eggs when they were places in different solutions.

Which statement best describes the role of the cell membrane in this model?

• The cell membrane is an impermeable barrier that prevents water from entering the cell

• The cell membrane allows solutes to enter the cell, which causes the cell to shrink.

• The cell membrane allows water to enter and leave the cell.

• The cell membrane removes solutes from the environment.

In the early 1900s a scientist hypothesized a link between DNA and the production of proteins in the cytoplasm. However, the fact that DNA could not be found outside the nucleus led scientists to believe that another substance was also involved int he synthesis of protein in the cytoplasm. In the 1940's scientists performed an experiment that ultimately identified the site of protein synthesis. They also identified the molecule responsible for transporting information from the nucleus to the site of protein synthesis. What was this newly identified molecule?

• a gene

• mRNA

• ATP

• Thymine

This diagram shows cellular activity across a cell membrane. Which two processes does this diagram most directly model?

• Energy conversions and synthesis of new molecules

• Synthesis of new molecules and homeostasis

• Transport of molecules and energy conversions

• Homeostasis and transport of molecules

Which molecule synthesized by plants is a major source of energy for cellular processes in both plants and animals?

• wax

• nucleic acid

• glucose

• chlorophyll