transport in cells

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Across
  1. 2. Movement of substances against the concentration gradient, requiring energy (6, 9)
  2. 4. The movement of particles from an area of high concentration to low concentration
  3. 6. A membrane that only allows certain substances to pass through (9, 9)
  4. 7. The barrier that controls entry and exit of substances in a cell (4, 8)
  5. 12. A gas that diffuses out of the blood into the alveoli (6, 7)
  6. 15. A type of transport that does not require energy
  7. 16. Cells that control the opening and closing of stomata in leaves (5, 5)
  8. 18. Substances absorbed by root hair cells via active transport
  9. 19. Tiny pores on the underside of leaves where gas exchange occurs
  10. 20. A gas that diffuses from alveoli into the blood
Down
  1. 1. The difference in concentration between two areas (13, 8)
  2. 3. An adaptation of exchange surfaces that shortens the diffusion distance (4, 8)
  3. 5. Tiny air sacs in the lungs adapted for gas exchange
  4. 8. The molecule that moves by osmosis
  5. 9. Finger-like structures in the small intestine for absorbing nutrients
  6. 10. Extensions of root cells that increase surface area for water uptake (4, 5)
  7. 11. The overall movement of particles during diffusion or osmosis (3, 8)
  8. 13. The diffusion of water across a partially permeable membrane
  9. 14. Small blood vessels with thin walls to allow efficient exchange
  10. 17. A sugar absorbed into the bloodstream from the small intestine