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LC Biology
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LC Biology

Biology - Variation & Evolution

Variation

Variation : differences amongst members of the same species. (E.g. hair colour/height)

Variation can be inherited (in genes) or acquired (learning over time E.g. ability to speak French)

Species

Inherited Variation amongst species occurs by two mechanisms:

1)Sexual reproduction: produces variation due to meiosis (see Chapter 13: The Cell Cycle)

2) Mutation: produces variation due to changes in the amount or structure of DNA.

Result: change in sequence of bases - no protein produced. Can affect a somatic cell (anc could cause cancer) or a gamete (and be passed onto offspring)

Mutations can occur spontaneously – for... (More)

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LC Biology

Expermients Summary - Section B

EXPERIMENT QUESTIONS

1. (a) TEST FOR REDUCING SUGAR:

FOOD SOURCE: Glucose (monosaccharide)

CHEMICAL USED: Benedict’s solution (blue)

HEAT REQUIRED: Yes (thermostatically controlled water bath)

+ RESULT: Colour change BLUE to BRICK RED

- RESULT: No colour change (stays blue)

CONTROL: Water + Benedict’s (non-reducing sugar)

PURPOSE OF CONTROL: Acts as a comparison

1. (b) TEST FOR STARCH:

FOOD SOURCE: Potato/ Bread

CHEMICAL USED: Iodine (red/yellow), using a dropper due to small volume needed

HEAT REQUIRED: No

+ RESULT: Colour change RED/ YELLOW to BLUE/BLACK

- RESULT: No colour change (stays red/yellow)

CONTROL: Water and Iodine

1. (c) TEST FOR... (More)

  • Nitrogen-fixing bacteria, which convert atmospheric nitrogen to nitrates
  • Nitrifying bacteria, which convert ammonia to nitrates/nitrites.
  •  Denitrifying bacteria, which convert nitrates to nitrogen gas

The 5-carbon sugars ribose and deoxyribose are important components of nucleotides, and are found in RNA and DNA, respectively. The sugars found in nucleic acids are pentose sugars.