Biology term test papers

We are neither affiliated with the author of this essay nor responsible for its content. The process by which all living things have developed from primitive life forms through changes occurring over billions of years is evolution. All living things arose through a long history of changes formed by physical and chemical processes that are still taking place. It is possible that all organisms can be traced back to the origin of life from inanimate matter.

Biology term test papers

We are neither affiliated with the author of this essay nor responsible for its content. To study the effect of environmental changes in the permeability of living beet root cells.

Cut a beet root into slices approximately 2mm thick.

Biology term test papers

Use a cork bore to cut out thirty-five 35 slices. Place the discs in a mL beaker and rinse thoroughly in cool running tap water. The red pigment collected comes from the damaged cells and can be used to analyze the chemical nature of the pigment. The pigment in a beet, anthocynanin, should be analyzed before beginning.

This can be done simply by first adding a few drops if concentrated acid to a sample if beet juice. The resulting solution can be compared to a second sample made Biology term test papers adding a few drops if concentrates base to another sample of beet juice.

Note the colours of each. Given stock solutions of 0. Place five 5 beet root discs in each of the 7 test tubes. Leave them for 15 minutes and then record your observations. Agitate gently and continue to observe them at minute intervals until no further changes occur.

Prepare beet root discs as for Procedure A. The number required will depend on the control you design. Place five 5 of the discs in a test tube containing 10 mL of distilled water and 2 mL of ethanol.

Design a control for this investigation. Agitate gently and periodically for 15 minutes and record your observations.

A/L Biology Colombo School Papers

Analyzing anthocynanin by adding concentrated acid and base to beet juice Mixture Observations recorded Few drops of concentrated acid added to a sample of beet juice -Concentrated acid caused the anthocynanin to turn to a slightly lighter shade of pink.

Few drops of concentrated vase added to a sample of beet juice -Concentrated base caused the anthocynanin to turn a transparent yellow. Serial Dilution Intervals 0. Designing A Control The control our group designed for this investigation was to have one test tube with 10 mL of distilled water 2 mL of ethanol.

This way both test tubes would have a total of 12 mL and 5 beet roots each. Test tube with 12 mL of water Test tube with 10 mL of water and 2 mL of ethanol -very little pigment lost -light pink in colour -beets moved twirled when agitated -very little pigment lost -only a light tint of pink could be seen -beets did not move when agitated, they remained at the bottom of the test tube -traces of oil were present in the test tube Discussion 1.

What relationship exists between the concentration of acid or base solution and the pH? Bases start at as low as and acids are up to 1. How is the membrane affected by the different pH values of the solutions? What changes have the tested solutions created in the structure of the membrane?

The pH value of Hydrochloric acid is 0, and the pH value of the Sodium hydroxide is The anthocynanin then permeated through the membrane. Since the pH value of the distilled water is 7, which is neutral, caused no damage to the cell membrane. The closer the substance was to neutral the more osmosis pressure was create around the sell membrane.Biology I Third Term Test Gr13 AND Thambaru Wijesekara March 8, Download Now (Right Click -> Save Target As) A part .

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Biology term test papers

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