biology paper 2 - B6

• What is sexual reproduction?


  The fusion of male and female gametes
• What type of cell division is involved in sexual reproduction?

  Meiosis
• What type of cell division is involved in asexual reproduction?

  Mitosis
• What is meiosis?


  Cell division that produces 4 daughter cells (gametes), each with half the number of chromosomes
• What are the male and female sex chromosomes in humans?


  XX for female and XY for male
• What are the male and female gametes in flowering plants?

  Pollen (male) and ovule (female)
• What is the genetic material in cells called?

  DNA
• What is the structure of DNA?

  Double helix
• What is a gene?

  A small section of DNA that codes for a particular amino acid
• What are alleles?

  Different forms of the same gene
• What is a recessive allele?


  An allele that needs to be present twice to express a trait
• What is a dominant allele?


  An allele that is always expressed, even if only one copy is present
• What is a genome?

  The entire genetic material of an organism
• Define the term homozygous.

  The two alleles present in an organism are the same
• Define the term heterozygous.

  The two alleles present in an organism are different
• How many chromosomes do normal human body cells have?

  46 chromosomes (23 pairs)
• Why is studying the human genome important?

  It can help identify genetic mutations linked to diseases
• What is the structure of DNA primarily described as?

  Double helix
• What are the basic building blocks of DNA called?

  Nucleotides
• What are the three components of a nucleotide?

  Phosphate, sugar, and base
• How many different types of bases are there in DNA?

  4
• What do the letters A, T, C, and G stand for in DNA?

  Adenine, thymine, cytosine, guanine
• What forms the sugar phosphate backbone of DNA?

  Phosphate of one nucleotide bonds to sugar of another
• What is the role of the sugar phosphate backbone in DNA?

  It forms a protective outer casing
• What is complementary base pairing?

  A pairs with T, C pairs with G
• What does the term genetic code refer to?

  The sequence of bases in DNA
• What is a gene?

  A sequence of bases coding for a protein
• What is a triplet in the context of DNA?

  A group of three bases coding for an amino acid
• What happens to the chain of amino acids after it is formed?

  It folds up to form a protein
• Why do different proteins have unique shapes?

  Different sequences of amino acids
• What role do hormones play in the body?

  Carry messages around the body
• What do structural proteins do?

  Add strength to cells and tissues
• What is the process of making proteins called?

  Protein synthesis
• What are the two main steps of protein synthesis?

  Transcription and translation
• What happens during transcription?

  A gene of DNA is copied into mRNA
• What is the role of mRNA in protein synthesis?

  It carries the genetic code from DNA
• What does mRNA stand for?

  Messenger RNA
• Why can't DNA leave the nucleus?

  Because DNA is too large to exit
• What is the structure of mRNA compared to DNA?

  mRNA is shorter and single-stranded
• What base does mRNA contain instead of thymine?

  Uracil