Interactions of Macromolecules and Cellular Functions SB1c

What best explains why the structure of glucose seen here is best suited to provide the "go-to" energy source for the mitochondria to perform cellular respiration?

• Glucose is a polysaccharide which can be broken down slowly to release energy over time.

• Glucose is stored in the liver of animals for long term energy.

• Glucose is a monomer which allows it to be broken down rapidly as a quick energy source.

• Glucose forms long, stringy chains which make up easily- digestible fiber to fuel the mitochondria.

Answer explanation

As a monomer subunit of carbohydrates, glucose is very small and requires little cellular energy to be broken down in glycolysis, the first step of cellular respiration which occurs in the cytoplasm. The small by-products of glucose can then enter the mitochondria to make ATP in aerobic cellular respiration.

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GSE Biology

SB1c

Phospholipids are a special kind of lipid which make up the phospholipid bilayer in cells seen in this image. What about the structure of phospholipids makes the plasma membrane of cells semi-permeable?

• Hydrophilic phosphate heads of the phospholipids restrict access of certain substances.

• Hydrophobic fatty acids tails of phospholipids facing towards the center of the cell membrane create a protective barrier which only allows some substances to pass freely into the cell, while restricting others.

• The combination of phosphate and fatty acids in the membrane allows all substances to move freely in and out of the cell.

• Proteins actively regulate the passage of molecules in and out of the phospholipid bilayer.

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GSE Biology

SB1c

Consider the four types of polysaccharides pictured here. Which makes the best energy storage molecules for plants, and why? You may choose more than one if appropriate.

• Amylose because it forms a helix (spiral), it packs tightly into the cell and breaks down more slowly.

• Cellulose because it forms long strands.

• Amylopectin because the branches provide greater surface area for energy storage.

• Glycogen because more branches provide the greatest surface area for energy storage.

Answer explanation

The question is asking about energy storage in plants,not animals. Due to its helical shape, Amylose packs more tightly in plant cells and breaks down more slowly than Amylopectin. Amylopectin is faster to break down as the branches provide greater surface area for chemical breakdown.

Tags

GSE Biology

SB1c

What properties of cellulose makes it such a strong substance for the cell walls of plants?

• It contains a high percentage of phospholipids which allows it to be a semipermeable barrier around the cell.

• It is easily broken down and digested by enzymes in most animals and plants.

• It forms a helical (spiral) structure which makes for strong barriers and support around the outside of the cell.

• It is a stringy, linear molecule which can hold up to water pressure and is not easily broken down by most enzymes.

• It allows nothing to pass through the cell wall.

Tags

GSE Biology

SB1c

Proteins have the most diverse functions of all of the macromolecules. They are involved in cell transportation, play a role in cell signaling, and function as enzymes in chemical reactions. What characteristic of protein structure best explains this?

• Since proteins are only composed of carbon, hydrogen and oxygen they are readily assimilated into the body in order to perform many different functions.

• The very small size of proteins allows them to fit into more places in the cell and perform a wide variety cellular functions which other macromolecules cannot.

• Each of the amino acids contain unique R-groups, and the four increasing levels of complex protein structure impart unique functions to proteins.

• The nucleotides which make up proteins code for unlimited numbers of cellular functions.

• Proteins can be found in so many different sources, from beans to nuts to eggs to meat.

Tags

GSE Biology

SB1c

DNA and RNA are both nucleic acids, but perform different jobs in different parts of the cell. What characteristic of RNA structure best explains its unique role in cellular functions?

• RNA's ribose sugar makes it better suited for cellular energy storage than DNA's deoxyribose sugar

• The phosphate-sugar backbone of RNA makes it stronger and better for supporting the cellular membrane.

• The uracil in RNA allows it to carry genetic code and condense into chromosomes by binding with histone proteins.

• RNA is single-stranded and is able to fit through the nuclear pores to carry DNA's message outside the nucleus to direct protein synthesis.

Tags

GSE

Biology

SB1c

What is it about the structure of saturated fats that makes them excellent molecules for long term energy storage?

• They have double bonds between carbons which give double the energy when they are broken.

• Their long hydrocarbon chains break down much easier than the sugar rings of carbohydrates.

• The fatty acids tails form long straight chains which pack together tightly for energy storage in the body of organisms.

• Their variable R groups attached to the central carbon atom store energy for long periods of time.

What about DNA's structure forces it to remain in the nucleus while RNA is able to travel in and out of the nucleus and out to the cytoplasm and ribosomes?

• DNA is single stranded so it is too long to leave the nucleus.

• DNA is double stranded and is not able to exit through the nuclear pores of the nuclear envelope.

• The deoxyribose sugar of DNA is too large to leave the nucleus.

• DNA has more nitrogen bases which makes it too large to leave the nucleus.

Why does the structure of starchy foods make such good fuel for athletes? Choose all that apply for credit.

• There are many individual saccharides linked together in a starch.

• Fiber is not easily digested by humans so it stays with the athlete for a long time before it provides energy.

• Each time a starch undergoes hydrolysis to remove a link in the long chains of a polysaccharide, energy is released.

• The cell walls of starchy foods are not easily broken down so they sit in your stomach and intestines for a long time.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS3-4

Why would a person whose blood sugar has dropped reach for an apple over a piece of whole grain toast?

• There is a lot of starch in an apple ready to provide energy.

• The apple contains simple sugars which are small and fast acting in the body.

• The apple has more fiber which will raise the blood sugar more quickly.

• The apple has carbohydrates which are easier for the body to break down.

Tags

SB1c

GSE Biology