BIO 181 - Unit 2 Exam

The formation of the complex molecules in living orgnanisms is made possible by what property or carbon?

Carbon forms up to 4 covalent bonds

What do contact-dependent signaling and paracrine signaling have in common?

Cells release a signal that affects neighboring cells

Which of the following correctly describes bases that pair with each other in the DNA double helix?

Cytosine bonds with guanine

The key structural difference between DNA and RNA is:

DNA contains a different sugar than RNA

Osmosis describes the movement of water from an area of high to low solute concentration.

False

How might a plant cell compensate for the excessive membrane fluidity that occurs during prolonged exposures to elevated temperature?

Alter the lipid composition to have longer phospholipid tails and fewer double bonds

Which of the following are physical stimuli that influence plant responses?

CO2, light, water vapor, gravity

What process best characterizes Ca2+ movement from the cytosol (low Ca2+ concentration) into the endoplasmic reticulum (high Ca2+ concentration)?

Calcium movement involves active transport

What type of bonding is likely to occur between two water molecules or strands of DNA?

Hydrogen

The strongest chemical bonds are:

covalent bonds

Isotopes are different forms of the same element that

differ in their number of neutrons

Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs?

Presence of aquaporin channels for facilitated diffusion of water

The process that most involves the selective uptake of a specific cargo molecule into the cell through receptor binding and aggregation.

Receptor-mediated endocytosis

Sodium concentrations are higher outside and glucose concentrations are higher inside the cell. Using the same membrane protein for Na+ and glucose transport, what is it called when a Na+ electrochemical gradient is used to drive glucose transport into the cell against its concentration gradient?

Secondary active transport

Subunits (monomers) sometimes build up to form a macromolecule (polymer). Which of the listed molecules is NOT a monomer of a polymer?

Steroid

The movement of sucrose and H+ into the cell by the same membrane protein reflects the actions of what type of transporter?

Symporter

Which membrane component is most important for allowing large, charged molecules to pass through the membrane?

Transmembrane proteins

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

True

Ion gradients across the membrane drive numerous cellular functions.

True

Plant behavior is defined as response to stimuli.

True

The presence of integral proteins allows membranes to be selectively permeable to certain molecules

True

Whether a signaling molecule operates locally or over long distances, it must bind to a specific receptor to elicit a cellular response.

True

Carbohydrate assembly occurs by

a dehydration reaction between monosaccharides that form polysaccharides and disaccharides

The production of second mesengers in signal transduction offers at least two advantages, speed and

amplification

Fats and fatty acids

are insoluble in water

In the periodic table, the value that refers to the number of protons and neutrons is

atomic mass

If the tight junctions in the intestine were disrupted

bacteria could move from the intestines into the bloodstream causing an infection

The addition of a strong acid like HCl to an aqeuous solution would result in

both the release of H+ and a decrease in pH

Which level of organization is common to all life forms?

cell

The process through which cells can detect and respond to signals in their extracellular environment is called:

cell communication

Following a meal, glucose must move from the gut lumen where there is a high glucose concentration into the intestinal cell where there is a relatively low level of glucose. This movement is called:

facilitated diffusion

Cyanide binds and impairs one of the molecules involved in the synthesis of ATP. The target organelle for cyanide must be:

mitochondria

A substrate binding to an enzyme is most similar to a signal molecule binding to a:

receptor

Roots contain starch-heavy plastids known as:

statoliths

The grouping or classification of a species is termed:

taxonomy

The atomic number of an atom is

the number of protons in the atom

In some cases, just a few hormone molecules binding to the surface of a cell can trigger a very large response because:

the signal is amplified by activation of enzymes that each catalyze multiple reactions

Which is the largest molecule?

A polysaccharide

_________ bind two or more ions or molecules and transport them in opposite directions across a membrane.

Antiporters

If a person's ability to form steroids in his/her body was destroyed, what functions would be affected?

Estrogen would no longer be produced in the body

A dehydration reaction that builds larger molecules from smaller units requires the addition of a water molecule.

False

How does a macrophage (immune cell) consume a bacteria?

Phagocytosis

Sodium ions move from one cardiac muscle cell to an adjacent cell causing them to contract in unison. This is an exampe of:

direct intracellular signaling

When one oxygen atom shares two pairs of electrons with another oxygen atom, O2 is formed via a(n)

double covalent bond

A community of organisms interacting with their physical environment is a/an

ecosystem

When insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake, this is an example of:

endocrine signaling

You inject a dye into a cell and observe that it moves into adjacent cells. This would occur through _____.

gap junctions

During a period of low water availability, the prokaryotic structure that would protect a cell from desiccation (drying out) is the

glycocalyx

Gravitropism is defined as:

growth in response to the force of gravity

Water

has cohesive properties

Eukaryotes differ from prokaryotes, in part because eukaryote cells:

have a membrane-bound nucleus

Whether the external temperature is hot or cold, birds maintain an internal body temperature of approximately 40°C. This is an example of

homeostasis

The LEAST hydrophilic substance is

oil

A cell secretes a growth factor that binds to receptors on neighboring cells causing them to proliferate. This is an example of:

paracrine signaling

Boa constrictors on an island are an example of a(n) ____.

population

The seqence of amino acids in a protein is its _____ structure.

primary

A cell wall is present in

prokaryotic and plant cells

The macromolecule composed of amino acids is a

protein

The nucleus of an atom is composed of

protons and neutrons

A protein's _____ structure contains helixes and sheets that result from hydrogen bonding between carboxyl and amino groups of the polypeptide chain.

secondary

The best way to describe cellular membranes is

semifluid with lipid rafts

Diabetics can be given insulin that binds to receptors on cells throughout the body increasing glucose uptake. Insulin is an example of a

signal

The gonads produce steroids. The specific steroid-producing organelles in gonad cells are:

smooth endoplasmic reticulum