bio ch 2&3

a polyunsaturated fat contains which of the following?

A polyunsaturated fat contains many double bonds between carbon atoms. A saturated fat contains as many hydrogen atoms as possible ("saturated" in hydrogen) and does not contain any carbon-carbon double bonds.

which of the following molecules provides the energy that maintains concentration gradients across cell membranes?

Adenosine triphosphate provides the energy that maintains concentration gradients across cell membranes. Abbreviated ATP, this molecule powers the transport of substances up their concentration gradients in a series of steps that require energy.

which of the following is true regarding antioxidants?

Antioxidants inhibit the effects of free radicals. Free radicals are molecules with unpaired electrons in their valence shells, which makes them highly reactive with other molecules. They can damage cell membranes and anatomic structures, such as arteries. Antioxidants can limit this damage.

Many people believe that detox products, such as detox teas, will help them stay healthy by detoxifying the liver. With one exception, all of the following questions should be answered if this belief is to be supported.

Are detoxifying teas grown with organic practices without pesticide? Evidence is preliminary at best showing that these substances help relieve or treat the other listed conditions.

which of the following organelles or structures are present in animal cells but not plant cells?

Centrioles are present in animal cells but not in plant cells. These organelles are made of microtubules that help move chromosomes during cell replication and also form part of cilia and flagella.

which of the listed organelles consists of a series of membranous sacs and contains pigment molecules?

Chloroplasts are composed of a series of membranous sacs and contain pigment molecules. The pigment is chlorophyll, which absorbs some wavelengths of light energy to power photosynthesis.

which of the following organelles is not located in the cytoplasm of eukaryotic cells?

DNA is located in the nucleus of eukaryotic cells.

what are essential to amino acids?

Essential amino acids are those that the body cannot synthesize. As such, they must be ingested in food. Nonessential amino acids are synthesized by the body. Roughage consists of complex carbohydrates in the form of fiber from the diet. Plant proteins can be combined to to get all the essential proteins need.

which of the following best describes the process of facilitated diffusion across a cell membrane?

Facilitated diffusion across a cell membrane is the movement of a solute down its concentration gradient with the help of membrane proteins. The process does not require energy.

which of the following substances uses facilitated diffusion to cross the cell membrane?

Glucose uses facilitated diffusion to cross the cell membrane. This kind of passive transport uses protein carriers. It does not require energy.

In the phospholipid bilayer of the plasma membrane, the heads of the phospholipids are ___________ and face ___________.

In the phospholipid bilayer of the plasma membrane, the heads of the phospholipids are hydrophilic and face outward toward the watery solutions inside and outside the cell. The bilayer also contains proteins and other structures that move about in the membrane, forming a fluid mosaic structure.

what is the function of the plasma membrane in a photosynthetic eukaryotic cell?

It controls protein synthesis in the cell.

Substance X is more concentrated outside the cell than inside the cell. Substance Z is more concentrated inside the cell than outside the cell. Assume that both substances can pass freely through the cell membrane. Over time, what will happen?

Molecules of X will move inside the cell, and molecules of Z will move outside the cell until equilibrium is reached. Substances move from regions of higher concentration to regions of lower concentration across a membrane, which is called "movement down the concentration gradient."

Substance R is too large to diffuse across the cell membrane or to be transported across by a protein. Molecules of Substance R can, however, cross the membrane and exit the cell. By which of the listed processes do they cross?

Molecules that are too large to diffuse across cell membranes, such as those of Substance R, are moved out of a cell by exocytosis. The substance is enclosed in a membrane-bound vesicle that fuses with the plasma membrane and releases its contents outside the cell.

which of the listed substances does not contain carbon?

Of the listed substances, minerals do not contain carbon. For this reason, they are called "inorganic."

_____ are to cells as organs are to the body.

Organelles are to cells as organs are to the body because organelles (organs) have specific jobs and work together to keep the cell (body) functioning properly.

which of the following is a correct paring of an organelle and its function

Ribosome and protein assembly is the correct choice. Ribosomes are attached to the endoplasmic reticulum or float free in the cytoplasm. They are the site where proteins are assembled.

which of the following is an accurate statement about roughage in the diet?

Roughage in the diet, in the form of fiber, consists of complex carbohydrates that provides bulk to feces. This indigestible substance helps move along the products of digestion and prevent constipation.

which choice shows the substances that rely on facilitated diffusion to cross the cell membrane?

Substances that rely on facilitated diffusion to cross the cell membrane include hydrophilic molecules and charged molecules. This process is "powered" by concentration gradients but relies on the help of proteins to cross. Water, carbon dioxide, and oxygen pass freely across the cell membrane down their concentration gradients without the aid of proteins. Water also moves across with the aid of membrane channels formed by proteins called aquaporins.

Sven has moved to a town near the Arctic Circle, an area that receives relatively little sunlight. Sven eats a very healthy diet. His doctor tells him, however, "Now that you live in this part of the world, you should take a vitamin supplement." Which of the following vitamin supplements should Sven take?

Sven's doctor wants him to take supplemental vitamin D. Vitamin D is the only vitamin that the body can manufacture, but sunlight is required for this process. Therefore, people living in regions with sparse sunlight are often advised to take vitamin D supplements.

Imagine a balloon is made from a membrane that's permeable to water but not sugar molecules. How would the balloon be affected if it is filled with a 50% sugar solution and then placed in a beaker of water?

The balloon would get larger as it gains water.

Which of the following is a correct pairing between the commercial process that adds hydrogen atoms to unsaturated fats and one of its products?

The correct pairing between the commercial process that adds hydrogen atoms to unsaturated fats and one of its products is hydrogenation and margarine. Hydrogenation adds hydrogen atoms to unsaturated fats under pressure, producing a saturated fat that is solid instead of liquid and that has a long shelf life. One product produced in this way is margarine.

some molecules, such as glucose, require proteins for transport across the cell membrane. this method does not require energy. why is this form of transport a type of diffusion?

The form of membrane transport that requires proteins is a type of diffusion because it relies on concentration gradients. Substances move down their concentration gradients with the assistance of proteins embedded in the lipid bilayer. Because the concentration gradient drives the movement, no energy is required.

what is the important structural difference between rough er and smooth er?

The important structural difference between rough endoplasmic reticulum (ER) and smooth ER is that rough ER has ribosomes attached to it; smooth ER does not. Ribosomes are the site of protein synthesis.

we eat to gain macronutrients. what substances are included in the term macronutrients?

The macronutrients that we need to consume are water, carbohydrates, fats, and proteins. Water is essential for disposing of wastes and dissolving and dispersing other nutrients. Nucleic acids, vitamins, and minerals are necessary, but they are not dietary macromolecules and are ingested as components of the listed macronutrients.

what role do vitamins play in the body?

Vitamins serve as coenzymes to speed up chemical reactions in the body.

When placed in solutions with different concentrations of salt, animal cells may change their shape. Which of these processes determines whether the cells expand, shrink, or remain the same shape?

When placed in a solution, animal cells expand, shrink, or remain the same shape because of osmosis, which is the movement of water across the cell membrane from a region of its own higher to its own lower concentration.

Which molecule requires the most ATP to be used for moving across a plasma membrane?

an ion moving against a concentration gradient

what molecule is composed of one or more sugars?

carbohydrate

what is a deficiency of water in the body?

dehydration

How would amino acids and calcium ions from the bloodstream move across a plasma membrane?

facilitated diffusion

Which process does not involve molecules moving across cell membranes?

hydrogenation

what characteristic applies to the interior of a phospholipid bilayer?

hydrophilic

what happens to excess protein stored in the body?

it is stored as fat

why is oxygen considered highly electronegative?

it pulls electrons toward itself

what are nutrients that the human body required in large quantities?

macronutrients

what particles are found in the nucleus of an atom?

neutrons and protons

in which eukaryotic cell structure are ribosomes made?

nucleolus

Some antibiotics disrupt bacterial phospholipids. Which cell component would be affected by such antibiotics?

plasma membrane

which chemical condition describes the electrons in a water molecule being shared unequally between the hydrogen and oxygen atoms?

polar

which substance is a macronutrient?

potassium

which type of lipid includes sex hormones such as testosterone and estrogen?

steroids

what protein fibers help form the framework of structural support for cells.

sytoskeletal

how would the permeability of the phospholipid bilayer of plasma membranes be described?

the bilayer is differentially permeable.

which component of amino acids accounts for the differences in their properties

the side group