BIO 181 Exam 2

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

Cells release a signal that affects neighboring cells.

What structure easily distinguishes a plant cell from an animal or bacterial cell?

Chloroplast

In Barrow, Alaska, the sun does not set for several months in the summer. Based on what you know about photoperiodism, what type of plant is most likely to flower during the summer in Barrow?

Day-neutral plants

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

False

If a specimen contains 30% adenine in its DNA, how much cytosine will there be?

20%

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

Eukaryotes differ from prokaryotes because eukaryotic cells ___________.

Have a membrane-bound nucleus

____________ bonding is likely to occur between H2O molecules or DNA.

Hydrogen

The organelles most likely to have the ability to divide and reproduce themselves (like a cell) would be _____________ & _______________.

Mitochondria Chloroplasts

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.

A cell wall is present in:

Prokaryotic AND plant cells

A diet of unsaturated fats is better because __________________.

Saturated fats are packed closer together and it breaks down energy less efficiently and forms unnecessary fat deposits.

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

Symporter

What makes phospholipids good at forming cellular membranes?

The polar and nonpolar regions create an amphipathic bilayer of phospholipids.

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

Transmembrane proteins

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

True

Plant behavior is defined as response to stimuli.

True

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

True

The function of a cell is related to the amount of surface area it has. Why?

True. A cell with the same mass can increase surface area with structures like microvilli that enhance absorption functions.

The production of second messengers in signal transduction offers at least two advantages, speed and ____________.

amplification

A cell secretes a growth factor that binds to receptors on its own membrane, preventing it from proliferating. This is an example of _________________.

autocrine signaling

If the tight junctions in the intestine were disrupted _____________

bacteria could move from the intestines to the bloodstream causing an infection.

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

cell communication

Plant cell walls contain __________.

cellulose

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 ATP synthesis. The target organelle for cyanide must be ____________.

mitochondria

An amino acid is to a protein as a ________ is to a nucleic acid.

nucleotide

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

receptor

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

receptor-mediated endocytosis.

Glycogen is to animal cells as ________ is to plant cells.

starch

Roots contain starch-heavy plastids known as:

statoliths

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 catalyze multiple reactions

What is the largest molecule?

A polysaccharide

An explanation with a substantial amount of evidence is called. (the closest thing to "fact" in science)

A theory

___________ bind two or more ions or molecules and transport them in the opposite direction across a membrane.

Antiporters

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

False

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

direct intercellular signaling

Hormones are released from one cell and act on other cells in distant organs. This is an example of __________.

endocrine signaling

For heart muscles to beat in a coordinated rhythm, ions must move from one cell to the next 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

Which is not a lipid?

glycogen

All organic molecules contain __________.

hydrogen and carbon

When placed in an aqueous solution, amphipathic molecules will orient themselves with ____________________.

hydrophobic hydrocarbon chains in the middle and hydrophilic head groups facing the water

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

paracrine signaling

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

phagocytosis

Gap junctions in animal cells are most similar to ________ in plant cells.

plasmodesmata

Sickle cell anemia is a condition in which red blood cells exhibit a characteristic "sickle" shape. This arises from a mutation or change in one of the amino acids found in hemoglobin. A single amino acid mutation would affect a protein's ___________ structure.

primary

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

proteins

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

secondary

The best way to describe cellular membranes is ____________.

semifluid with lipid rafts