Science Biology Cell Biology

How does the structure of this enzyme help with its function?

• The enzyme's shape complements the substrate's shape, so it only catalyzes specific reactions.

• Since the enzyme is larger than the substrate, catalytic reactions can occur within the enzyme itself.

• The enzyme's active site is amorphous and can change its shape to fit any substrate.

• Since the enzyme's shape matches the substrate's shape, it catalyzes only reverse reactions.

Proteins are used for many structural functions such as in the actin and myosin in muscle or as a part of the cytoskeleton scaffolding that maintains cell shape. What other main function do proteins serve?

• as enzymes to control the rate of reactions and regulate cellular activity

• as coding for genotypic expression and phenotypic traits

• as cellulose to form the major structural component of plant cell walls

• as waterproof membranes to regulate the transport of molecules in and out of the cell

Which of the following is true about nucleic acids?

I. Nucleic acids always consist of a five-carbon sugar, a nitrogenous base, and one or more phosphate groups.

II. Both DNA, which stores genetic information and encodes protein sequences, and RNA, which is involved in the direct production of proteins, are nucleic acids.

III. Nucleic acids are usually insoluble in water and are used for long term energy storage.

IV. Glucose, cellulose, and starch are examples of nucleic acids found in most cells.

• II only

• I and II only

• I, II, III, and IV

• I, III, and IV only

A student is given a small amount of unknown tan-colored liquid substance. This unknown liquid is placed into a glass of water and mixed. Despite mixing, the tan liquid remains separated from the water and collects as a large droplet at the top. Which of the macromolecule groups is this liquid most likely to be a member of?

• Carbohydrates

• Proteins

• Nucleic Acids

• Lipids

Lipids are organic macromolecules that serve a variety of purposes. What is the most important role of lipids?

• to store energy

• to build muscles

• to oxygenate blood

• to metabolize sugar

Sugars are a type of _______. They are produced by plants and release energy when they are broken down into smaller molecules.

• carbohydrate

• lipid

• protein

• hydrocarbon

Tags

NGSS.MS-LS1-7

Which of the following best describes a carbohydrate?

• Carbohydrates are organic macromolecules that are made up of carbon, hydrogen, and oxygen atoms and are used for energy storage or as structural molecules.

• Carbohydrates are composed of amino acid monomers and are involved in cell signaling, cell transport, immune responses, and the cell cycle.

• Carbohydrates are organic macromolecules that are insoluble in water and have the ability to store energy for extended periods of time.

• Carbohydrates always consist of a five-carbon sugar, a nitrogenous base, and one or more phosphate groups and are used to store genetic information.

Organisms must be able to adapt to a changing external and internal environment. An organism's ability to maintain a stable internal environment is known as homeostasis. How does a cell's membrane help an organism maintain homeostasis?

• Cell membranes use a large portion of the cell's energy supply.

• Cell membranes control the substances that enter or leave cells.

• Cell membranes protect the cell organelles from large doses of radiation.

• Cell membranes directly control the temperature of the cell.

Tags

NGSS.HS-LS1-3

The proteins necessary for life are assembled by the ribosomes of cells. These proteins include enzymes, which are proteins that can reduce the activation energy needed for certain chemical reactions. One very important role that enzymes play in eukaryotic cells is to allow energy production to occur by catalyzing the chemical reactions involved in cellular respiration.

Suppose an enzyme that is involved in cellular respiration is assembled by a ribosome. Where will this enzyme need to be transported in order to perform its function?

• to a chloroplast

• to a mitochondrion

• to a vacuole

• to the nucleus

Tags

NGSS.HS-LS1-7

Cells use _______ to take in large molecules or other cells.

• active transport by endocytosis

• active transport by carrier proteins

• passive transport by diffusion

• passive transport by osmosis