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Description
Flashcards by Nicholas Haddad, updated more than 1 year ago
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Created by Nicholas Haddad
over 7 years ago
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| Question | Answer |
| Describe the structure and function of the cell membrane. | The cell membrane is made of a fluid phospholipid bilayer. Embedded in the membrane are transport proteins, which assist the movement of molecules into and out of the cell. Glycoproteins and glycolipids act as antennae that send and receive chemical messages. The cell membrane is selectively permeable, meaning that it can regulate the materials that enter and exit. |
| What materials get in and out of the cell? What regulates this and how? | The phospholipid bilayer allows certain materials to enter and others not to. The polarity, size and electric charge of a molecule determines whether it can pass through. Small hydrophobic molecules like oxygen and small uncharged polar molecules like water can pass freely through the bilayer. Larger uncharged polar molecules and ions are assisted by transport proteins. |
| Describe the importance of the concentration gradient to the movement of particles. | The concentration gradient is the difference in concentration across a distance. When molecules travel with the concentration gradient (high to low), energy isn't required. This allows many necessary molecules to enter cells from the bloodstream, such as oxygen. When molecules travel against their concentration gradient, energy is required to move them. |
| Explain the following: diffusion, facilitated diffusion, osmosis, passive transport, active transport, endocytosis and exocytosis. | Diffusion is the movement of molecules from high to low concentration, which is with the concentration gradient. Osmosis is the diffusion of water across a selectively permeable membrane. Facilitated diffusion diffuses molecules with the help of a gated or open protein channel. These are all examples of passive transport, which doesn't require energy. Active transport moves molecules against their concentration gradient, thus requiring energy. It uses transport proteins and might move a molecule of glucose from the blood into a cell (low to high). Endocytosis brings very large molecules into the cell by wrapping around them and pulling them in. Exocytosis gets rid of wastes and other materials by carrying them out of the cell. |
| What is the equilibrium of a cell? | The equilibrium of a cell is when the concentration of molecules inside and outside of the cell is equal. However, molecules still move randomly and may still move in and out of the cell. The equilibrium of a cell doesn't entail molecules to stop moving. |
| Describe hypo, hyper and isotonic solutions and what results from them. | When a cell is placed in a hypotonic solution, the concentration of water outside the cell is greater than inside of it, so water diffuses in, causing the cell to swell or burst. In plant cells, the outward pressure of water on the cell wall is called turgor. When a cell is placed in a hypertonic solution, the concentration of water inside the cell is greater than outside of it, so water diffuses out, causing the cell to shrink. When a cell is placed in an isotonic solution, the concentration of water inside and outside of the cell is equal, but molecules continue to move randomly. The cell remains the same size. |
| What adaptations do water living creatures have to efficiently exchange gases? | Water living creatures have gills to efficiently exchange gases. Gills have a tremendous amount of surface area and a system of countercurrent flow, allowing oxygen to diffuse into the bloodstream. |
| What adaptations do land living creatures have to efficiently exchange gases? | The most important adaptation land living creatures have to efficiently exchange gases is the internalization of their gas exchange system. This allows water to be conserved/not be lost. They also have oils, lipids and waxes on their skin/leaves to prevent water loss (and gas loss in plants). |
| Explain the human respiratory system. | Air enters the nasal or oral cavity (nasal cavity warms and filters it). It passes the pharynx, epiglottis and larynx, and into the trachea. As it travels down, it splits into one of the bronchi, and branches off through bronchioles until it reaches the alveoli. Here, oxygen diffuses into the bloodstream and CO2 diffuses from the blood into the alveoli. The CO2 then travels through the bronchioles, bronchi, trachea, past the larynx, epiglottis, pharynx and out the oral or nasal cavity. |
| What system do humans have to maintain homeostasis by eliminating wastes? Explain how the major organs of the system work to accomplish the task. (kidneys/nephrons/glomerulus) | Humans eliminate wastes through the urinary system. The kidneys are the major organs of this system, and they are composed of nephrons. The nephron has 3 main functions: filtration, reabsorption and secretion. Blood enters the glomerulus via the renal artery, and leaves via the renal vein. Here, blood pressure filters blood plasma, urea, glucose, amino acids (some), water and salts into the glomerular capsule. They pass into the tubule, which reabsorbs any materials still needed by the cell, such as glucose, amino acids, water and salts, which go into the network of capillaries surrounding the tubule. Later, excess materials or those forgotten earlier are secreted back into the tubule, and the materials exit through the collecting duct. This process helps our bodies to maintain homeostasis. |
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