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Biology Course Work

Essay by   •  October 9, 2015  •  Exam  •  3,270 Words (14 Pages)  •  1,144 Views

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Year 12 Biology Summaries

1.1        - identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to descibe their specificity on substrates.

Role of enzymes in metabolism:

  • all physical and chemical processes in cells
  • reaction speed = metabolic rate
  • enzyme- a biological catalyst (must be present or speeds up reaction)
  • reaction- biosynthetic pathway
  • enzyme may change during reaction, but reverts back by end
  • each enzyme acts on one compound only (substrate)
  • requires certain environment to be active
  • each cell makes different enzymes

Chemical composition:

  • built from amino acids, linked for peptide chains
  • 22 types of amino acids
  • linked in any sequence
  • protein molecules
  • folded to expose active site specific to substrate

Induced fit model

  • attaches to model to change shape

Lock and key model

  • substrate fits neatly into enzyme active site
  • disassemble to remain the same shape

  1. - identify the pH as a way of describing the acidity of a substance

                        Lower than 7 = acidic = H+        

pH Scale                               7 = neutral = H2O

                        Higher than 7 = basic = OH-

  • pH- describes acidity/alkalinity of a substance
  • pH extremes cause protein structure to denature permanently

1.S.1        - identify data sources, plan, choose equipment or resources and perform a first-hand investigation to test the effect of:

  • increased temperature
  • change in pH
  • change in substarte concentrations on the activity of named enzyme(s)

Increased / decreased temperature

  • used potato and bleach (H2O2, hydrogen peroxide)
  • 3 test tubes: one on ice, one at room temperature, one at 60oC (approx.)
  • found activity highest at room temperature, hot or cold extremes reduce reaction rates and therefore enzyme activity
  • therefore it is obvious there is a narrow optimum temperature range, outside of which enzyme activity significantly decreases

Change in pH

  • used potato and bleach (H2O2, hydrogen peroxide)
  • tested with 2 stengths of hydrochloric acid, distilled water and 2 strengths of sodium hydroxide
  • found activity highest at a pH of 7, a cell’s natural pH
  • therefore similar to the temperature results, there is a narrow optimum pH range, outside of which enzyme activity significantly decreases
  • optimum range = 7-9, neutral to mildly basic

Change in concentration

  • used Bromaline and milk
  • the higher the concentration of milk (the substrate), the faster the reaction with the enzyme (Bromaline) was

  1. - explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency

Internal maintenance & metabolic efficiency

  • major changes in environment = incativity = cell death
  • feedback systems monitor environment changes
  • if enzyme conditions are not in the optimal range, the organism will suffer
  • therefore metabolic efficiency decreases

  1. - descibe homeostasis as the process by which organisms maintain a relatively stable internal environment

Homeostasis

  • maintain a constant internal biochemical state
  • therefore metabolic and physiological functioning are maintained
  • two stages: normal state and counteraction state
  • if homeostasis isn’t present, cells die and the organism suffers

  1. - explain that homeostasis consists of two stages:
  • detecting changes from the stable state
  • counteracting changes from the stable state

The two stages of homeostasis

  • receptors always start working to detect changes that might disrupt the stable state of homeostasis
  • the counteracting stage takes measures to return the body to the stable state
  1. - outline the role of the nervous system in detecting and responding to environmental changes

Role of the nervous system

  • stimulus → receptors → conductor (sensory nerve) → control centre (central nervous system) → motor nerve → effector → response → back to receptors
  • CNS receives information on required body adjuctments for changes
  • sends instructions for appropriate feedback through motor nerves to the effector
  • adjustments made, loops back to CNS to check for any further required changes

  1. - identify the broad range of temperatures over which life is found compared with the narrow limits for individual species

  • there are narrow optimum temperature ranges for each individual species
  • outside these ranges the organism will suffer, perhaps being killed
  • life on our planet is found from temperatures far below freezing to incredibly hot
  • these temperature ranges and the life they support demonstrates diversity and evolution within organisms
  1. - compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation

                                        AND

1.S.3        - analyse information from secondary sources to describe adaptations and responses of Australian organisms that assist temperature regulation

  • echidna → hibernates when the weather gets colder → prevents losing heat through minimal movement → behavioural adaptation
  • some marsupials → licks fur → helps keep cool by saliva application → behavioural adaptation
  • whale → thick layer of blubber (fat) insulates against the cold waters of the ocean → structural adaptation
  • small mammals → surface area to volume ratio allows to lose more heat on hot days than a larger mammal → structural adaptation

  1. - identify some responses of plants to temperature change
  • some flowering plants withdraw the petals of the flowers in hot conditions, exposing less surface area to the heated environment surfaces
  • many will lose the flowers altogether and change the colour of their leaves to assist in absorbing heat instead of reflecting it during times of cold weather

2.1        - identify the form(s) in which each of the following is carried in mammalian blood:

  • carbon dioxide
  • oxygen
  • water
  • salts
  • lipids
  • nitrogenous waste
  • other products of digestion

  • carbon dioxide-  hydrogen carbonate ions in red cells and plasma
  • oxygen- oxyhaemoglobin in red cells
  • water- as water in plasma
  • salts- ions in plasma
  • lipids- chylomicron in plasma
  • nitrogenous waste- mostly urea in plasma
  • other products of digestion- separate molecules (glucose, amino acids etc) in plasma

  1. - explain the adaptive advantage of haemoglobin
  • each molecule hasa 4 active sites for oxygen to attach to
  • dissociates more easily at higher temperatures
  • dissociates more readily in electrolytes than pure solution
  • dissociates more readily at lower pH
  1. - compare the structure of arteries, capillaries and veins in relation to their function
  • arteries → thick wall, large diameter to allow high volumes of blood to be pushed through at once, leads to and from vital organs
  • veins → thin wall, diameter smaller than artery but a larger number to still allow efficient blood flow, connected to vital organs
  • capillaries → 1 cell thick wall, very narrow but copious amounts in body, spread from other major blood vessels to allow blood to be distributed around the body

2.S.1        - perform a first-hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water

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