biology

• What is the primary purpose of nitrogen in living organisms?

  Nitrogen is needed for making proteins for growth
• Why can't plants use nitrogen directly from the atmosphere?


  Plants cannot use nitrogen directly because it needs to be converted into mineral ions
• How do plants absorb nitrogen from the soil?

  Plants absorb nitrogen in the form of mineral ions such as nitrates
• How do neurotransmitters affect impulse direction?

  They ensure the impulse goes in one direction
• Which base pairs with adenine (A) in RNA?


  Uracil (U)
• What happens after RNA polymerase binds to the DNA?


  The two DNA strands separate, and RNA polymerase moves along one strand
• What ensures that the mRNA is complementary to the gene?


  Base pairing between the DNA and RNA
• What happens to the mRNA molecule after it is made?


  It moves out of the nucleus and joins with a ribosome
• What matches the order of amino acids brought to the ribosome?


  The order of the base triplets in mRNA
• What are base triplets in mRNA called?

  Codons
• What is the function of the anticodon in tRNA?


  It is complementary to the codon for the amino acid
• How does the pairing of codon and anticodon affect protein synthesis?


  It ensures that amino acids are brought to the ribosome in the correct order
• What happens to the amino acids at the ribosome?


  They are joined together to make a polypeptide (protein)
• Who identified the presence of dominant and recessive genes?

  Gregor Mendel
• If the DNA template strand sequence is ATGCTA, what would be the corresponding mRNA sequence?


  UACGAU
• If the DNA coding strand sequence is GATTACA, what would be the corresponding mRNA sequence?


  GAUUACA
• In a gene, if the DNA coding strand sequence is ATGGCCTAA, what would be the corresponding mRNA sequence?


  AUGGCCUAA
• What is the corresponding mRNA sequence for the DNA coding strand CGTATGCCA?


  CGUAUGCCA
• What is the complementary DNA sequence for TACCGGATT?


  TACCGGATT
• What is the mRNA sequence for the DNA coding strand ATGGCCTAA?


  AUGGCCUAA
• How do you convert a DNA coding strand to an mRNA sequence?


  By replacing T with U in the DNA sequence
• What is the mRNA sequence derived from the DNA coding strand CGTATGCCA?


  CGUAUGCCA
• What is the role of mRNA in protein synthesis?


  • Carries genetic information from DNA to ribosomes
  • Serves as a template for protein synthesis
  • Is relatively short-lived compared to DNA
  • Corresponds to a specific gene and protein
• What are the three main steps of translation?


  Initiation, elongation, termination
• What happens during the initiation phase of translation?

  mRNA binds to a ribosome and the start codon is recognized
• What signifies the termination phase of translation?

  A stop codon is reached
• What are the two main steps of protein synthesis?

  1. **Transcription**:

  • DNA unwinds
  • RNA polymerase creates mRNA
  • mRNA is processed and exits the nucleus

  1. **Translation**:

  • mRNA binds to ribosome
  • tRNA brings amino acids
  • Polypeptide chain is formed
  • Protein is released
• How do transcription and translation relate to each other in protein synthesis?


  Transcription produces mRNA in the nucleus, which is then used for translation in the cytoplasm to make proteins
• What is the function of RNA polymerase during transcription?

  It creates mRNA from the DNA template
• Why is mRNA considered temporary compared to DNA?


  Because mRNA is relatively short-lived, allowing for flexible protein production
• What is the significance of the start codon in translation?

  It signals the beginning of protein synthesis
• What is the role of tRNA during translation?

  tRNA brings amino acids to the ribosome and matches its anticodon to the mRNA codon
• How does the sequence of nucleotides in mRNA affect protein synthesis?


  It determines the sequence of amino acids in the protein
• What are the stop codons in translation?

  UAA, UAG, UGA
• If a DNA coding strand has the sequence ATG, what is the corresponding mRNA codon?


  AUG
• What is the primary function of messenger RNA (mRNA)?


  To carry genetic information from DNA to ribosomes
• What are the two types of sex chromosomes in humans?

  X and Y chromosomes
• Why are sex-linked disorders more likely to be seen in boys?


  Because boys have only one X chromosome, so any gene on it is expressed without competition
• What is an example of a sex-linked disorder?


  Colour-blindness
• What are the possible gametes and offspring phenotypes from a cross between an unaffected female carrier and an unaffected male?


  • Gametes: X (from female), Y (from male)
  • Offspring phenotypes:
  • Unaffected female (carrier)
  • Unaffected male
  • Colour-blind male
  • No possible colour-blind female offspring
  • 50% chance of colour-blind male offspring