Science: Biology

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Science: Biology
2010-11-03 03:14:30

DNA and Genes etc.
Show Answers:

  1. What does DNA stand for?
    DNA stands for Deoxyribose Nucleic Acid.
  2. What is DNA?
    DNA is genetic material. It is like a blueprint for every organism.
  3. What does DNA do?
    DNA codes and tells our cells how to make us and how we are.
  4. What is a double helix?
    Double Helix is the slight twist that sticks the two strands of a DNA fibre together.
  5. What is the DNA alphabet and what are the pairing rules for it?
    The DNA alphabet is: A, T, C and G. The pairing rules are that A always pairs with T and C always pairs with G.
  6. What do each of the letters in the DNA alphabet stand for?
    A stands for Adenine. T stands for Thymine. C stands for Cytosine. G stands for Guanine.
  7. What is a gene?
    A gene is an instruction manual for our body. They are the directions for all the proteins that make our bodies function.
  8. What are genes made of?
    Genes are made of DNA.
  9. How many genes do humans have?
    Humans have 25 000 genes.
  10. What is a chromosome?
    A chromosome is a compact unit which holds DNA.
  11. How many chromosomes does a human cell hold?
    A human cell holds 46 chromosomes.
  12. How are the human sex chromosomes labelled?
    The human sex chromosomes are labelled X and Y.
  13. What is the main difference between a sex cell and a body cell?
    A sex cell has only one set of chromosomes whereas body cells have two sets.
  14. What is heredity?
    Heredity is the passing of traits from parents to their children.
  15. In humans, how many chromosomes does each parent pass on to their offspring?
    Each parent passes 23 chromosomes to their offspring.
  16. What is a trait?
    A trait is a notable feature or quality in a person. These are passed from generation to generation.
  17. What are the types of traits that exist? Give explanations and examples.
    • - Physical Traits
    • Hair color, eye color or height
    • - Behavioral Traits
    • The way in which we act
    • Predisposition to a Medical Condition
    • The increased risk of getting a disease
  18. What are the three groups of chemicals that make up DNA?
    They are Bases (Adenine, Thymine, Guanine & Cytosine), Sugar (Deoxyribose) and Phosphates.
  19. How do the chemicals make the DNA molecule?
    The base pairs make up the rungs and the phosphates and sugars make up the sides. This is also known as the phosphate-sugar backbone.