Read the summary and the most important questions on MYP Biology: a Concept Based Approach | 9780198369950 | David Mindorff; Andrew Allott

• 5 Movement

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• What is a change to position called with respect for the environment, for e.g muscle constractions in arms?

  A change in position is called movement and it can be detected by comparing the position of something at different times.

• In what scales does change in positition occur?

  • Substances can move in and out of cells across the cell membrane, like water molecules leave cells through osmosis
  • Liquids, such as the blood in veins and arteries, and gases are pumped around in the body in a process known as mass flow
  • Different parts of an organism can be moved in relation to each other, through growth and muscle action
  • Whole organisms can move from one location to the other which is locomotion

• How are gasses exchanged in tissues through diffusion?

  Oxygen is used in areobic respiration and it moves around the tissue. The concentration is lower inside the cells than the blood passing through. Later carbon dioxide moves out as waste product.

• What is a mixture than contains dissolved material?

  That is a solution. The solute is the dissolved material in a solvent. Water is a solvent.

• What happens when two solutions are separated and the solute isn't let through?

  The solvent will move from the area with a lower salute concentration to the area of a high solute concentration.

• What is osmosis in water?

  Osmosis is the movement of water through a selectively permeable membrane from a lower to a higher concentration.

• 5.1 What is the relationship between gas exchange and respiration?

• How does gas exchange in a leaf through stomata?

  Photosynthesis occurs in the chloroplast in which carbon dioxide is used and oxygen is produced. This creates a concentration in which the carbon dioxide will diffuse in the leaf and oxygen to diffuse out of the leaf through the stomata.

• What happens when the stomata is open in a leaf?

  Whenever it is open water moelcules will pass through and it will evaporate from moist cellwalls inside the leaf creating a high concentration . If the concentration of water vapor outside is lower than it diffuses out through the stomata in a process called transpiration.

• 5.2 How does water move from roots to leaves?

• Why due transpiration the water cells inside the leaf do not dry out?

  This is because adhesion. When the water cell walls in a leaf lose water it is replaced with an equal amount of the nearest xylem vessel. The water is drawn through the wall of leaf cells by a type of capillary action as a sort of pulling force. The water isn't pulled apart from each other due the hydrogen bonds and this is property is cohesion. Water rises in the steam through a combined pull of transpiration and the cohesion of water molecules.

• 5.3 How do sugars move in plants?

• How do sugars move in plants?

  Plants make sugars 'carbohydrates' by photosynthesis in plants. To storage the carbohydrates or use it plants have a tissue for the transport of carbohydrates called phloem. A high concentration of sugar in the phloem near the source of production in the leaves draws water from the nearby xylem. This creates pressure and at the same time sugar is withdrawn at other location in the plant these are sinks. This causes water to leave the phloem by osmosis and so creates a low pressure.