Honors Bio - Membranes and Transport

Diffusion is the movement of

• water from low to high concentration

• particles from low to high concentration

• water from high to low concentration

• particles from high to low concentration

Answer explanation

Diffusion is the process where particles move from an area of high concentration to an area of low concentration. This is a fundamental concept in physics and chemistry. The correct answer is 'particles from high to low concentration' which accurately describes this process.

Tags

NGSS.MS-LS1-2

Large molecules and ions (polar molecules) can easily pass through the cell membrane without any help.

• true- they pass right through

• false- they need a protein channel

Answer explanation

The statement in the question is false. Large molecules and ions, which are polar, cannot easily pass through the cell membrane without assistance. They require a protein channel to facilitate their passage. This is because the cell membrane is selectively permeable and only allows certain substances to pass through.

A white blood cell engulfing a bacteria is an example of:

• endocytosis

• exocytosis

• cotransport

• facilitated diffusion

Answer explanation

The process of a white blood cell engulfing a bacteria is an example of endocytosis. Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of the cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material. This is how white blood cells engulf bacteria, making 'endocytosis' the correct answer to the question.

Osmosis is a form of ______________. 

• Passive Transport

• Active Transport

Answer explanation

Osmosis is a form of Passive Transport. In this process, molecules of a solvent tend to pass through a semipermeable membrane from a region of low solute concentration to an area of high solute concentration. It is a natural phenomenon that doesn't require any external energy, hence it's classified as Passive Transport.

ATP is a form of energy used in...

• Passive Transport

• Active Transport

Answer explanation

ATP, or Adenosine Triphosphate, is a form of energy used in active transport. Active transport is a process that moves molecules into or out of a cell from a region of lower concentration to a region of higher concentration. This process requires energy, which is provided by ATP. Therefore, the correct answer is 'Active Transport'.

The boundary that REGULATES movement of molecules into and out of the cell

• Cytoplasm

• Cell Membrane

• Chloroplast

• Cell Wall

Answer explanation

The cell membrane is the correct answer because it is the structure that regulates the movement of molecules into and out of the cell. The other options, cytoplasm, chloroplast, and cell wall, do not have this function. The cell membrane is a selectively permeable barrier, allowing certain substances to pass while blocking others.

Tags

NGSS.MS-LS1-2

The membrane is a bilayer built MAINLY of these:

• Carbohydrates and DNA

• Hormones and nucleic acids

• Proteins and carbohydrates

• Phospholipids and proteins

Answer explanation

The correct answer is 'Phospholipids and proteins'. The membrane is a bilayer structure primarily composed of phospholipids and proteins. Phospholipids form the basic structure, while proteins perform most of the functions. Other options like carbohydrates and DNA, hormones and nucleic acids, proteins and carbohydrates are not the main components of the membrane.

Phospholipids are made of (CHOOSE 2):

• phosphate head

• ribosomes

• carbohydrate chains

• fatty acid tails

Answer explanation

Phospholipids, the major component of cell membranes, are composed of two main parts: a phosphate head and fatty acid tails. The phosphate head is hydrophilic, meaning it is attracted to water, while the fatty acid tails are hydrophobic, meaning they repel water. This unique structure allows phospholipids to form a lipid bilayer, a critical component of all cell membranes. Ribosomes and carbohydrate chains are not components of phospholipids.

The phosphate heads of phospholipids ATTRACT water because

they are (CHOOSE 2):

• non-polar

• polar

• hydrophilic

• hydrophobic

Answer explanation

The phosphate heads of phospholipids attract water because they are polar and hydrophilic. Polar substances have a charge and can therefore interact with water, which is also polar. Hydrophilic substances are 'water-loving' and will tend to interact with water as well. Both these properties make the phosphate heads of phospholipids attract water.

The fatty acid tails of phospholipids REPEL water because they are:

• Non-polar

• polar

• hydrophilic

• hydrophobic

Answer explanation

The fatty acid tails of phospholipids repel water because they are non-polar. In chemistry, 'non-polar' means that the substance does not have a net electrical charge, which makes it unable to interact with polar substances like water. This is why the fatty acid tails of phospholipids, being non-polar, repel water.