Human reproduction

• What are the two main types of reproduction?

  Sexual and asexual reproduction
• What are the advantages of sexual reproduction?

  It produces variation in offspring and decreases the chance of the whole species becoming extinct
• What are the advantages of asexual reproduction?

  It uses less energy and is faster as organisms do not need to find a mate, and in favorable conditions lots of identical offspring can be produced
• How does the process of fertilization work in plants?

  1. Pollen grains land on the stigma
  2. Pollen tube grows from the pollen grain down the style into the ovary and to the ovule
  3. The male nucleus travels down the pollen tube and fuses with the female egg nucleus in the ovule, forming a zygote
  4. The zygote undergoes mitosis to form a seed
  5. The ovule wall becomes the seed coat and the ovary becomes the fruit
• What are the three main conditions needed for seed germination?

  Water, oxygen, and warmth
• What are the main structures and functions of the male reproductive system?

  • Testes: Produce sperm and testosterone
  • Sperm duct: Carries sperm
  • Penis: Passes urine and semen out of the body
  • Urethra: Tube inside penis to carry urine or semen, with a ring of muscle to stop them mixing
• What are the main structures and functions of the female reproductive system?

  • Ovary: Contains ova (female gametes)
  • Oviduct: Connects ovary to uterus, lined with ciliated cells to push ovum towards uterus
  • Uterus: Has thick lining for implantation of fertilized egg
  • Cervix: Ring of muscle at lower end of uterus to keep fetus in place
  • Vagina: Muscular tube leading to inside of body
• What are the secondary sexual characteristics in females?

  Breast development, menstrual cycle begins, growth of body hair, widening of hips, increased height
• What are the secondary sexual characteristics in males?

  Growth of penis and testes, production of sperm, growth of facial and body hair, muscle development, voice lowering
• What are the key hormones and their roles in the menstrual cycle?

  • Oestrogen: Causes thickening of uterus lining, peaks on day 10 then falls
  • Progesterone: Maintains thick uterus lining, inhibits LH and FSH, peaks 3 days after ovulation
  • FSH: Causes maturation of egg in ovary
  • LH: Stimulates release of egg during ovulation

  
• What is the role of the placenta during pregnancy?

  It allows diffusion of glucose, oxygen and amino acids from the mother's blood to the developing fetus, and passes carbon dioxide and urea from the fetus to the mother's blood
• What is the role of the amniotic fluid during pregnancy?

  It protects the fetus and cushions any rough movement, and when labor begins the amnion breaks and the fluid comes out
• What is a gamete?

  An organism's reproductive cell, with half the normal number of chromosomes
• What is a genome?

  The entire DNA of an organism
• What is a chromosome?

  A structure in the nucleus made up of a long strand of DNA
• What is a gene?

  A short section of DNA that codes for a protein
• What is an allele?

  The different forms of a gene that an individual inherits
• What is a dominant allele?

  Only one copy is needed for it to be expressed and observed
• What is a recessive allele?

  Two copies are needed for it to be expressed and observed
• What is a homozygous genotype?

  When both inherited alleles are the same
• What is a heterozygous genotype?

  When one of the inherited alleles is dominant and the other is recessive
• What is a genotype?

  The combination of alleles an individual has
• What is a phenotype?

  The physical characteristics that are observed in the individual
• What is codominance?

  When neither allele is dominant over the other, so both contribute to the phenotype
• What are the four nitrogenous bases in DNA?

  A, C, G, T
• How does the structure of DNA allow it to store genetic information?

  DNA is a double helix made of two strands with complementary base pairing, where each group of three bases codes for an amino acid to make a protein
• What are the key steps in the process of protein synthesis?

  1. DNA helix is unwound and unzipped, 2) mRNA nucleotides match to complementary bases on the DNA strand, 3) mRNA strand is created and leaves the nucleus, 4) mRNA attaches to ribosomes in the cytoplasm to synthesize the protein
• What are the strengths and weaknesses of qualitative research methods?

  Strengths:

  • Provides in-depth, rich data
  • Flexible and adaptable to new information
  • Captures complex phenomena

  
  

  Weaknesses:

  • Time-consuming and labor-intensive
  • Potential for researcher bias
  • Limited generalizability
  • Difficulty in replicating results
• What are the key adaptations of insect-pollinated and wind-pollinated plants?

  Insect-pollinated plants have large, bright petals and scented nectar to attract insects, while wind-pollinated plants have small, dull petals, no nectar, and smooth, light pollen that can be easily carried by the wind
• What are the key steps in the process of asexual reproduction through runners and cuttings?

  Runners: Strawberry plants grow horizontally over the soil surface and put down roots to form new plants. Cuttings: Tissue samples are scraped from the parent plant, placed in agar growth medium, and develop into plantlets that are then planted into compost.
• What are the key structures and functions of the placenta during pregnancy?

  The placenta allows diffusion of glucose, oxygen and amino acids from the mother's blood to the developing fetus, and passes carbon dioxide and urea from the fetus to the mother's blood. It also takes over the production of progesterone.
• What is the role of the amniotic fluid during pregnancy?

  It protects the fetus and cushions any rough movement, and when labor begins the amnion breaks and the fluid comes out.
• What forms the backbone of a nucleotide?

  A sugar-phosphate group
• What are the four different organic bases in DNA?

  A, C, G, T
• What does complementary base pairing mean?

  C joins to G and A joins to T
• What does each group of three bases code for?

  An amino acid
• What are chromosomes made up of?

  Long molecules of DNA
• What are the steps of protein synthesis?

  1. DNA unwinds and unzips
  2. mRNA nucleotides match to DNA
  3. mRNA forms a template strand (transcription)
  4. mRNA moves to ribosomes
  5. mRNA bases read in threes (translation)
  6. Carrier molecules bring amino acids
  7. Amino acids connect to form proteins
  8. Protein folds into a 3D structure
• What is the role of ribosomes in protein synthesis?

  Read mRNA to code for amino acids
• What is a Punnett square used for?

  To predict offspring genotypes and phenotypes