Question 1

Facilitated diffusion is limited by

Accepted Answer

Facilitated diffusion requires carrier proteins in the membrane to transport molecules across the membrane. Therefore, the availability and number of carrier proteins can limit the rate of facilitated diffusion. The other choices, such as osmotic pressure and the size of the cell, are not directly related to facilitated diffusion.

Question 2

Organisms that feed on dead organisms for nutrients are called ______.

Accepted Answer

Saprobes are organisms that obtain nutrients by feeding on dead organisms, plant debris, and other detritus. They are also known as decomposers or saprophytes. Examples of saprobes include fungi and many types of bacteria.

Question 3

The cell wall will help prevent the cell from bursting in ______ conditions.

Accepted Answer

In hypotonic conditions, the external solution has a higher water concentration compared to inside the cell. This leads to water influx into the cell, causing it to swell and potentially burst. However, the presence of a cell wall in plants, fungi, and bacteria can prevent this bursting by providing structural support and preventing the cell from expanding beyond its maximum capacity.

Question 4

Saprobes do not need a carbon source for growth and metabolism.

Accepted Answer

Saprobes are organisms that obtain their nutrition by absorbing dead and decaying organic matter, which serves as a source of carbon for their growth and metabolism. Therefore, they do require a carbon source to survive.

Question 5

Which organism has a challenge to maintain cellular electrolyte and fluid balance in its environment?

Accepted Answer

All of the listed organisms have a challenge in maintaining cellular electrolyte and fluid balance in their environment. The protozoan in a fresh water lake needs to regulate water uptake to avoid bursting, while the bacterium in a fresh-water lake may face osmotic stress due to changes in the concentration of solutes in the water. The bacterium in Great Salt Lake has to deal with high salt concentration, which can cause water to leave the cell and disrupt cellular processes.

Question 6

Which of the following microorganisms would find hypotonic conditions most damaging?

Accepted Answer

Protozoa are single-celled eukaryotic organisms that lack a rigid cell wall and rely on contractile vacuoles to regulate water balance. In hypotonic conditions, water enters the cell rapidly, causing it to swell and potentially burst. Bacteria, algae, cyanobacteria, and fungi all have cell walls that provide some protection against osmotic pressure changes.

Question 7

Nutrient absorption is mediated by the ______.

Accepted Answer

Nutrient absorption occurs across the cell membrane, which is selectively permeable and allows certain nutrients to pass through. The other options listed are not involved in nutrient absorption.

Question 8

Which of the following require the cell to use energy?

Accepted Answer

Endocytosis requires the cell to use energy to engulf and import material into the cell. Osmosis, diffusion, and facilitated diffusion do not require energy as they are passive transport mechanisms.

Question 9

Contractile vacuoles are

Accepted Answer

Contractile vacuoles are specialized organelles in some single-celled organisms, such as protozoa and certain algae, used to expel excess water from the cell. This mechanism helps to regulate the cell's osmotic pressure, particularly in freshwater environments where the outside environment is hypotonic (lower in solute concentration) compared to the inside of the cell.

Question 10

Mediated transport of polar molecules and ions across the plasma membrane utilizes a(n)_____ carrier that binds to the substance and causes a conformational change to allow its movement across the membrane.

Accepted Answer

Polar molecules and ions cannot easily pass through the hydrophobic lipid bilayer of the plasma membrane, and therefore require the use of proteins to transport them across. These proteins, known as carriers or transporters, bind specifically to the substance they are transporting and undergo a conformational change to move it across the membrane. Porins are not specific to any particular substance and allow for the non-specific diffusion of small polar molecules, while lipids and enzymes do not play a direct role in mediated transport.

Question 11

You want to experiment with microbial growth in various nutrients,so you inoculate a loopful of E.coli into a tube of honey.Which statement best describes what you expect to happen and why?

Accepted Answer

The answer of You want to experiment with microbial growth...

Question 12

When whole cells or large molecules in solution are engulfed by a cell,this endocytosis is specifically termed ______.

Accepted Answer

Phagocytosis is the process by which a cell engulfs large particles or whole cells, such as bacteria or dead cells. This type of endocytosis is sometimes referred to as "cellular eating." Facilitated diffusion, facilitated transport, and pinocytosis involve the transport of smaller molecules and ions across membranes, but not the engulfing of large particles. Exocytosis is the opposite process of endocytosis, where material is released from a cell.

Question 13

Diffusion of water through a semipermeable membrane is called ______.

Accepted Answer

Diffusion of water through a semipermeable membrane is specifically called osmosis.

Question 14

A saprobe with a cell wall will utilize extracellular digestion.

Accepted Answer

A saprobe is an organism that feeds on dead and decaying organic matter. If it has a cell wall, it will need to break down the organic matter outside of its cell before it can absorb it. This is known as extracellular digestion, and is common in saprobes such as fungi and bacteria.

Question 15

The movement of substances from higher to lower concentration across a semipermeable membrane via a specific protein carrier but without energy expenditure is called ______.

Accepted Answer

Facilitated diffusion is the movement of substances from higher to lower concentration across a semipermeable membrane via a specific protein carrier but without energy expenditure. This is in contrast to active transport, which requires energy, and diffusion, which occurs without the aid of a protein carrier. Endocytosis involves the engulfment of substances by the cell via the cell membrane, and osmosis specifically refers to the diffusion of water molecules.

Question 16

Obligate saprobes can adapt to a living host.

Accepted Answer

Obligate saprobes are microorganisms that require dead organic matter to survive and cannot live on a living host. They lack the mechanisms to invade and colonize living tissue.

Question 17

The movement of substances from lower to higher concentration across a semipermeable membrane via a specific protein carrier and cell expenditure of energy is called ______.

Accepted Answer

Active transport is the movement of substances against the concentration gradient (from lower to higher concentration) with the help of specific protein carriers and energy expenditure by the cell. Osmosis is the movement of water across a semipermeable membrane from higher to lower concentration. Diffusion is the movement of particles from higher to lower concentration without the help of protein carriers or energy expenditure. Endocytosis is the process by which cells engulf external material and bring it inside the cell. Facilitated diffusion is the movement of particles from higher to lower concentration with the help of protein carriers but without energy expenditure.

Question 18

The process by which a cell uses ATP to enclose a substance in its membrane,by forming a vacuole and engulfing it,is called ______.

Accepted Answer

Endocytosis is the process by which a cell uses ATP to enclose a substance in its membrane, by forming a vacuole and engulfing it. Active transport uses ATP to move substances against their concentration gradient, facilitated diffusion uses transport proteins to move substances down their concentration gradient, diffusion is the passive movement of substances from high to low concentration, and osmosis is the diffusion of water across a selectively permeable membrane.

Question 19

Bacteria living in a freshwater stream that are transferred to ocean water would

Accepted Answer

The answer of Bacteria living in a freshwater stream that...

Question 20

The movement of molecules from an area of high concentration to an area of lower concentration is called ______.

Accepted Answer

The movement of molecules from an area of high concentration to an area of lower concentration is called diffusion. Osmosis is a type of diffusion that specifically refers to the movement of water molecules across a semi-permeable membrane. Facilitated diffusion and active transport both involve the movement of molecules across a membrane, but they require the assistance of specific proteins and/or the input of energy, respectively. Endocytosis refers to the process by which cells engulf external materials and bring them into the cell.

Quiz 15: Host Defenses II: Specific Immunity and Immunization