EDEXCEL GCSE Science BIOLOGY UNIT B2 The components of life

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  • Created by: hanna
  • Created on: 11-09-12 19:18

Topic 1 The building blocks of cells

  • the function of the components of a bacterial cell including chromosomal DNA, plasmid DNA, flagella and cell wall
  • the function of the components of a plant cell including chloroplast, large vacuole, cell wall, cell membrane, mitochondria, cytoplasm and nucleus.
  • the function of the components of an animal cell including cell membrane, mitochondria, cytoplasm and nucleus
  •  plant and animal cells can be studied in greater detail with a light microscope
  • changes in microscope technology have enabled us to see cells with more clarity and detail than in the past, including simple magnification calculations
  •  a gene is a section of a molecule of DNA and that it codes for a specific protein
  • a DNA molecule as
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Topic 1 The building blocks of cells

  • a) two strands coiled to form a double helix
  • b) strands linked by a series of complementary base pairs joined together by weak hydrogen bonds:
  • (i) adenine (A) with thymine (T)
  • (ii) cytosine (C) with guanine (G)
  • to extract DNA from cells
  • the structure of DNA was discovered, including the roles of the scientists Watson, Crick, Franklin and Wilkins
  • HT only: the implications of sequencing the human genome (Human Genome Project) and of the collaboration that took place within this project
  •  the process of genetic engineering, including the removal of a gene from the DNA of one organism and the insertion of that gene into the DNA of another organism
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Topic 1 The building blocks of cells

  • the advantages and disadvantages of genetic engineering to produce GM organisms, including:
  • a) beta carotene in golden rice to reduce vitamin A deficiency in humans
  • b) the production of human insulin by genetically modified bacteriac) the production of herbicide-resistant crop plants
  •  the division of a cell by mitosis as the production of two daughter cells, each with identical sets of chromosomes in the nucleus to the parent cell, and that this results in the formation of two genetically identical diploid body cells.
    •  mitosis occurs during growth, repair and asexual reproduction
    • at fertilisation, haploid gametes combine to form a diploid zygote
    • the division of a cell by meiosis as the production of four daughter cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes
    • cloning is an example of asexual reproduction that produces genetically identical copies
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Topic 1 The building blocks of cells

HT only: Be able to demonstrate an understanding of the stages in the production of cloned mammals, including:

a) removal of diploid nucleus from a body cell

b) enucleation of egg cell

c) insertion of diploid nucleus into enucleated egg cell

d) stimulation of the diploid nucleus to divide by mitosis e implantation into surrogate mammals

  • the advantages, disadvantages and risks of cloning mammals
  •  stem cells in the embryo can differentiate into all other types of cells, but that cells lose this ability as the animal matures
  • the advantages, disadvantages and risks arising from adult and embryonic stem cell research
  •  the order of bases in a section of DNA decides the order of amino acids in the protein
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Topic 1 The building blocks of cells

  • HT only:  the stages of protein synthesis, including transcription and translation:
  • a) the production of complementary mRNA strand in the nucleus
  • b) the attachment of the mRNA to the ribosome
  • c) the coding by triplets of bases (codons) in the mRNA for specific amino acids
  • d) the transfer of amino acids to the ribosome by tRNA
  • e) the linking of amino acids to form polypeptides
  • each protein as has its own specific number and sequence of amino acids, resulting in different-shaped molecules that have different functions, including enzymes
  •  gene mutations change the DNA base sequence and that mutations can be harmful, beneficial or neither.
  •  enzymes as biological catalysts
  • 1.27 Be able to demonstrate an understanding that enzymes catalyse chemical reactions occurring inside and outside living cells, including:
  • a) DNA replication
  • b) protein synthesis
  • c) digestion
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Topic 1 The building blocks of cells

  •  the factors affecting enzyme action, including:
    • a) temperature
    • b) substrate concentration
    • c) pH
  •  enzymes are highly specific for their substrate
  • the action of enzymes in terms of the ‘lock-and-key’ hypothesis
  •  enzymes can be denatured due to changes in the shape of the active site
  • Revise any investigations you did on the factors that affect enzyme activite!!!

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Topic 2 Organisms and energy

2.1 Know that respiration is a process used by all living organisms that releases the energy in organic molecules.

2.2 Be able to explain how the human circulatory system facilitates respiration, including:

a) glucose and oxygen diffuses from capillaries into respiring cells

b) carbon dioxide diffuses from respiring cells into capillaries.

2.3 Be able to define diffusion as the movement of particles from an area of high concentration to an area of lower concentration.

2.4 Be able to demonstrate an understanding of how aerobic respiration uses oxygen to release energy from glucose and how this process can be modelled using the word equation for aerobic respiration.

glucose + oxygen ==> water + carbon dioxide (+ energy)

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2.5 Revise any investigations on the effect of exercise on breathing rate and heart rate.

2.6 Be able to explain why heart rate and breathing rate increase with exercise.

2.7 Be able to calculate heart rate, stroke volume and cardiac output, using the equation cardiac output 5 stroke volume 3 heart rate

2.8 Be able to demonstrate an understanding of why, during vigorous exercise, muscle cells may not receive sufficient oxygen for their energy requirements and so start to respire anaerobically

2.9 Be able to demonstrate an understanding of how anaerobic respiration releases energy from glucose and how this process can be modelled using the word equation for anaerobic respiration
2.10 Know that the process of anaerobic respiration releases less energy than aerobic respiration
2.11 Be able to describe how a build-up of lactic acid requires extra oxygen to break it down.

Know this is called excess post-exercise oxygen consumption or EPOC (formerly known as oxygen debt)

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