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Life Science Exam 1
Part three of exam cards (Chapter 3)
| Term | Definition |
|---|---|
| Which organelles or structures are present in plant cells? | - Mitochondria - Rough endoplasmic reticulum - Central vacuole - Plasma membrane - Cell wall; Centrioles are present in animal cells but not in plant cells |
| What do centrioles do? | These organelles are made of microtubules that help move chromosomes during cell replication and also form part of cilia and flagella. |
| What organelle is only present in plant cells? | The central vacuole is present only in plant cells. It is a fluid-filled sac containing sugars and pigments that also helps maintain pressure inside the cell |
| In the phospholipid bilayer of the plasma membrane, the heads of the phospholipids are ________ and face __________. | hydrophilic; outward; 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 |
| Match each organelle with the function it performs. | * Converts food to ATP - Mitochondrion * Assembles proteins - Ribosome * Contains enzymes to recycle cell parts - Lysosome * Produces lipids and steroids - Smooth endoplasmic reticulum * Produces ribosomes - Nucleolus |
| What are ribosomes attached to? | The endoplasmic reticulum; when the surface is covered with ribosomes, it is called the Rough endoplasmic reticulum |
| Which choice shows the substances that rely on facilitated diffusion to cross the cell membrane? | Hydrophilic molecules and charged molecules; This process is “powered” by concentration gradients but relies on the help of proteins. Water, carbon dioxide, and oxygen pass across the cell membrane down their concentration gradients w/o proteins |
| Which of the following is a true statement 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 |
| Which of the listed organelles consists of a series of membranous sacs and contains pigment molecules? | Chloroplasts; The pigment is chlorophyll, which absorbs some wavelengths of light energy to power photosynthesis. |
| Which of the following substances uses facilitated diffusion to cross the cell membrane? | Glucose; This kind of passive transport uses protein carriers. It does not require energy. Active transport requires energy, passive does not |
| Sven has moved to a town near the Arctic Circle, an area that receives relatively little sunlight. His DR tells him "you should take a vitamin supplement.” Which of the following vitamin supplements should Sven take? | 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. |
| We eat to gain macronutrients. What substances are included in the term macronutrients? | 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 |
| Which of the listed substances does not contain carbon? | Minerals; For this reason, they are called “inorganic.” |
| What are essential amino acids? | Amino acids the body cannot synthesize; |
| 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? |
| 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? | It relies on concentration gradients. A concentration gradient is a gradual change in the concentration of a substance between two areas, where molecules naturally move from a region of high concentration to a region of low concentration |
| 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 wll move outside the cell until equilibrium is reached. |
| Which of the following best describes the process of facilitated diffusion across a cell membrane? | Movement of a solute down its concentration gradient with the help of membrane proteins |
| A polyunsaturated fat contains which of the following? | 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 organelles is not located in the cytoplasm of eukaryotic cells? | DNA; DNA is located in the nucleus of eukaryotic cells. Lysosomes, rough endoplasmic reticulum, mitochondria, and chloroplasts are located in the cytoplasm. |
| Which of the following is a correct pairing between the commercial process that adds hydrogen atoms to unsaturated fats and one of its products? | 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. |
| What role do vitamins play in the body? | They serve as coenzymes to speed up chemical reactions; A coenzyme is defined as an organic molecule that binds to the active sites of certain enzymes to assist in the catalysis of a reaction |
| Which of the following is an accurate statement about roughage in the diet? | It consists of complex carbohydrates and provides bulk to feces; his indigestible substance helps move along the products of digestion and prevent constipation. It is in the form of fiber |
| What is the important structural difference between rough endoplasmic reticulum (ER) and smooth ER? | Rough ER has ribosomes attached to it; smooth ER does not; Ribosomes are the site of protein synthesis. |
| What is the endoplasmic reticulum? | A network of membrane-bound sacs and tubes within a cell's cytoplasm, primarily responsible for the production, processing, and transport of proteins and lipids, |
| 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. |
| 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? | Osmosis; this is the movement of water across the cell membrane from a region of its own higher to its own lower concentration. |
| ________ are to cells as organs are to the body. | Organelles; 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. |
| 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? | Exocytosis; Exocytosis is the process of moving substances out of the cell. Endocytosis is the movement of substances into the cell. |
| True or False: One of the symptoms of severe dehydration is hallucinating. | True; Mild dehydration can cause fatigue; severe dehydration can lead to hallucinations, heat stroke, and death |
| Which vitamin is fat soluble? | Vitamin E; Vitamin E is fat soluble and cannot be synthesized by the body |
| Which food may provide your body with the most micronutrients? | Raw broccoli; Fresh vegetables are more nutritious than cooked vegetables because cooking leaches out vitamins and minerals |
| True or False: A healthy diet can provide all of the nutrients that you need | True; Most people who are eating a wide variety of healthy whole foods are getting all of the nutrients they need from their diet |
| Which function can be performed by the amino acids obtained from the breakdown of meats? | Building enzymes; enzymes are proteins that are built from amino acids |
| What cell structure is involved in the digestion of substances in cells? | Lysosome; Lysosomes are sacs of digestive enzymes that degrade proteins, carbohydrates, and fats; they can engulf targeted molecules and organelles for recycling |
| True or False: Ribosomes are produced by the rough endoplasmic reticulum. | False; Ribosomes are produced in the nucleolus. Some ribosomes then attach to the rough endoplasmic reticulum |
| Where do most cellular respiration reactions take place? | Mitochondrion; The mitochondrion is the location of many of the reactions of cellular respiration |
| True or False: The process shown in the illustration will continue moving glucose until the concentration of glucose molecules is greater on the inside of the cell than on the outside | (The image is of a concentration gradient) False; The process of facilitated diffusion continues until the concentration of molecules is equal on both sides of the cell membrane. |
| True or False: If a cell immersed in a solution gets larger and bursts, the initial concentration of water outside of the cell was greater than the concentration of water inside the cell. | True; Water moved down the concentration gradient into the cell, which caused it to burst |
| Which molecule could move across a plasma membrane the easiest? | Carbon dioxide; Carbon dioxide can move across a plasma membrane by simple diffusion |
| Simple diffusion vs. facilitated diffusion | In simple diffusion, Molecules, atoms, or ions move through a semipermeable membrane without the help of proteins; Facilitated diffusion, on the other hand, occurs through the action of transmembrane proteins such as carrier proteins, |
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