Bio181 Unit 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

The key structural difference between DNA and RNA is

DNA contains a different sugar than RNA.

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.

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

False

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

False

What structural component makes fat an efficient macromolecule able to store large amounts of energy?

Fats have long chains of C-H bonds, which store large amounts of energy.

If a specimen contains 30% adenine (A) in its DNA, how much cytosine (C) will it contain?

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.

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

Calcium movement involves active transport.

Which is not a lipid?

Glycogen

Isotopes are different forms of the same element that

differ in their number of neutrons.

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

endocrine signaling.

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

endocrine signaling.

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.

Why would a diet containing unsaturated fats that form triglycerides be better for an athlete when considering energy levels and health?

Saturated fats are packed closer together, making their breakdown for energy release less efficient and forming unnecessary fat deposits.

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

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

Symporter

If a person's ability to form steroids in his/her body was destroyed, what functions would be affected? (Check all that apply.)

The ability to produce insulin for glucose uptake would no longer exist. Hormone production in the endocrine system would no longer occur Estrogen would no longer be produced in the body.

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

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

True

T/F Ion gradients across the membrane drive numerous cellular functions.

True

T/F Lipids and carbohydrates can both be used by animals to store energy.

True

T/F Plant behavior is defined as response to stimuli.

True

T/F The presence of integral proteins allows membranes to be selectively permeable to certain molecules.

True

T/F 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. Is this statement true or false and why?

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

Carbohydrate assembly occurs by

a dehydration reaction between monosaccharides that form polysaccharides and disaccharides.

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

amplification

Fats and fatty acids

are insoluble in water

A cell responds to a signal it sent. This is an example of

autocrine signaling.

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 phenomenon through which populations of organisms change over several generations is termed

biological evolution.

The organelles most likely to have to ability to divide and reproduce themselves like a cell would be

both mitochondria and chloroplasts.

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.

A significant role played by pH buffers is to

limit major shifts in the amount of H+ and OH- in solution

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

mitochondria

The nucleus is to eukaryotes as the ________ is to prokaryotes.

nucleoid

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.

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

smooth endoplasmic reticulum.

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

starch

The grouping or classification of species is termed

taxonomy

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.

A variety of finch species within the Hawaiian Islands have acquired different types of beaks needed for utilizing specific food resources. What is the likely process by which these different species of finches came about?

vertical descent with mutation

What type of bonds form from the unequal sharing of electrons?

Polar covalent

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.

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

gap junctions

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

gap junctions

Our species is called Homo sapiens. The first word refers to which taxonomical grouping?

genus

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.

With an atomic mass of 16 and an atomic number of 8, it follows that oxygen __________. (Check all that apply.)

has 8 electrons can readily form bonds with 2 other atoms

Eukaryotes differ from prokaryotes, in part because eukaryote cells

have a membrane-bound nucleus.

A dehydration reaction

is used to form polymers.

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

Boa constrictors on an island are an example of a/an __________.

population

The sequence 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

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