biology test

• Hermaphrodites 


  species that have a functioning male and female reproductive organs in each individual
• selection 


  Tends to occur in unstable environments where the species has not reached its reproductive capacity, whereas K selection tends to occur in stable environment. comparison of the costs and benefits of external and internal fertilisation
• Many males have mate selection courtship rituals
• Sexual selection selects for characteristics that have little survival benefit for the individual, but increase their chances of mating
• Reversed sexual dimorphism occurs in some species
• Female choice involves females assessing honest signals of the fitness of males
• In lekking species, males gather to display at a lek, where female choice occurs success in male - male rivalry through conflict, increases access to females for mating
• Ecological niche 


  Is Multi - dimensional summary of tolerances and requirements of a species
• Fundamental Niche 


  Occupies in the absence of any interspecific competition
• Realised niche 


  Occupied in response to interspecific competition
• As a results of interspecific competition, competitive exclusion can occur, where the niches of two species are so similar that one declines to local extinction
• Where the realised niche are sufficiently different, potential competitors can co exist by resource partitioning
• one factor which can affect the set of proteins expressed by a given cell type


  Metabolic activity OR cellular stress OR response to signalling molecules OR diseased versus healthy.
• Sequence of the cell cycle


  G1, S, G2, M then cytokinesis
• Interphase

  Overall name for the stages of the cell cycle that prepare the cell for mitosis.
• Occurs during the S stage of interphase

  DNA replication
• Stage of mitosis when the chromosomes condense

  Prophase
• Anaphase


  Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell
• Sequence of mitosis stages

  Prophase, metaphase, anaphase, telophase the cytokinesis
• Cell growth

  Occurs during the G1 and G2 stages of interphase.
• Telophase

  Stage of mitosis when the two nuclei form.
• Metaphase


  Chromosomes line up in the middle of the cell
• P53

  Protein that blocks the cell cycle if DNA is damaged
• Apoptosis

  Programmed cell death triggered by signals that may originated within or out with the cell.
• Caspase cascade

  Process in which one proteinase activates the next inactive proteinase and this in turn activates more inactive proteinases in the cell death pathway.
• Proteinase

  Enzyme that catalysed the hydrolysis of proteins and peptides during apoptosis.
• Factors that trigger apoptosis

  Death signal from lymphocyte or irreparable DNA damage or growth factor absence.
• Cell Processes stimulated by p53 activation

  DNA repair or cell cycle arrested or cell death/ apoptosis
• DNAase

  Enzyme that catalyses the cleavage of DNA. Activated by cell death signals.
• Caspases


  Family of proteinases that play an essential role in apoptosis and are activated by cell death signals.
• Example of an intercellular response to a signal transduction pathway

  Change in uptake or secretion of molecules or rearrangement of the cytoskeleton or activation of proteins that regulate gene transcription.
• Signal transduction

  Receptor proteins convert an extra cellular signal to a specific intracellular response.
• Aquaporin


  Channel protein that allows water to move across the membrane down a water concentration gradient.
• Voltage-gated

  Nerve membrane channel proteins that open or close in response to a change in ion concentration gradient.
• Small molecules that can diffuse across the phospholipid bilayer of a cell membrane.

  Oxygen and carbon dioxide
• A molecule that binds to the myosin head causing it to detach from actin filaments so breaks the cross bridge.

  ATP
• Proteins involved in muscle contraction

  Actin and Myosin
• Phosphatase

  An enzyme that catalyzes the removal of a phosphate functional group from a protein (dephosphorylation).
• ATPase

  enzyme that catalyzes hydrolysis of ATP and uses the phosphate to phosphorylate itself.
• Molecule that leaves the myosin head causing a power stroke change of conformation that moves the actin filament contributing to muscle contraction.

  Phosphate (+ADP)