• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14
  15. 15

Structures and functions in living organisms. Revision Notes

Extracts from this document...


Structures and functions in living organisms 2.1 Describe the levels of organisation within organisms: Organelles -> Cells -> Tissues -> Organs -> Organ Systems. Smallest ------------------------------------------->Largest 2.2 Recognise cell structures, including the nucleus, cytoplasm, cell membrane, cell wall, chloroplast and vacuole 2.3 Describe the functions of the nucleus, cytoplasm, cell membrane, cell wall, chloroplast and vacuole Nucleus ? The largest organelle in the cytoplasm. This controls the cell. It contains chromosomes which carry genes. Cytoplasm ? The living material that makes up a cell. It is made up of many structures called organelles. Cell Membrane ? This is a thin layer on the surface of the cell. It is a partially permeable membrane between the cytoplasm and the outside as it controls which substances pass in either direction. Cell Wall ? This is a layer found outside the cell membrane. It is freely permeable so anything can pass through it. It is responsible to maintain Plant Turgor (the plant?s shape) Chloroplast ? These absorb light energy to make food in the process of photosynthesis Vacuole ? This is filled with cell sap, a store of dissolved sugar and solutes to provide energy for the plant, until it can create its own. 2.4 Describe the differences between plant and animal cells. Plant cells have a cell wall to maintain plant Turgor, whereas animal cells do not have this Plant cells have chloroplasts in order to carry out photosynthesis, whereas animals do not have this Plant cells have a large permanent vacuole, whereas plant cells do not have this. 2.5 Recall the chemical elements present in carbohydrates, proteins and lipids (fats and oils) Carbohydrates - Carbon, Hydrogen, Oxygen Proteins - Carbon, Hydrogen, Oxygen, Nitrogen (Sulphur in two amino acids) Lipids - Carbon, Hydrogen, Oxygen 2.6 Describe the structure of carbohydrates, proteins and lipids They are large molecules made up from smaller basic units: Carbohydrate (starch and glycogen) ...read more.


After 10-15 minutes, the indicator in the covered dish would turn from red to yellow, showing an increase in carbon dioxide because photosynthesis has not occurred. The indicator in the bright light petri dish would turn from red to purple as there would be less carbon dioxide since it is being used up by photosynthesis at a faster rate than it is being produced by respiration 2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes Air enters through the nose and mouth, travelling down the trachea. The trachea then sub divides into bronchi, which further subdivide into bronchioles, which lead to tiny air sacs where gas exchange takes place calls alveoli. Pleural membranes surround the lungs, an inner one attached to the lung surface, an outer one attached to the thoracic wall. Ribs protect the organs underneath, namely the heart and lungs; the ribs are joined together by intercostals muscles. The diaphragm is a large sheet that attaches to the thorax and sits underneath the lungs 2.45 understand the role of the intercostal muscles and the diaphragm in ventilation Inhalation - Diaphragm contracts and flattens in shape. External intercostals muscles contract, making the ribs move upwards and outwards These cause the volume of the thorax to increase, causing pressure to decrease, drawing air into the lungs Expiration - Diaphragm relaxes and returns to its dome shape. External intercostals muscles relax, allowing the ribs to move down and in. These cause the volume of the thorax to decrease and the pressure to increase, forcing air out of the lungs. 2.46 Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries * Walls are one cell thick, distance over which diffusion takes place is minimum * Moist lining, so the gases dissolve before they cross * A large surface area * High concentration gradient for gases, due to good blood supply 2.47 Understand the biological consequences ...read more.


Describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation Sweat is released on to the surface of the skin. The evaporation of this sweat needs heat energy, which it takes from the skin thus cooling the body down. If you are hot, vasodilation will occur; blood will travel in capillaries closer to the skin and these capillaries will get wider so more heat energy from the blood will be radiated from the skin I you are cold, vasoconstriction will occur; blood will travel through deeper vessels, which will be thinner preventing heat loss through radiation. Shivering may occur - rapid small contractions, which require energy from respiration, releasing heat energy at the same time. Body hair may be raised on the skin by hair erector muscles to trap a layer of warm air around the skin 2.90 Understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. ADH - Produced in pituitary gland - causes the walls of the collecting duct to beome more/less permeable to water depending on water levels in the blood. Insulin - Produced in the pancreas - Controls blood sugar levels - It converts excess glucose into glycogen, which is insoluble and stored in the liver. When there is not enough glucose in the blood, the pancreas secretes glucagon which turns glycogen back into glucose Adrenaline - Produced in the adrenal glands - Prepares the body for fight or flight, the crucial moment when an animal decide whether to fight or run for its life. Some of the effects of adrenaline are faster pulse, increased sweating, hair standing on end (to appear larger), paling of the skin (blood shunting) Testosterone - Secreted in the testes - Male sex hormone, which causes secondary sexual characteristics in boys and is needed for the production of sperm. Progesterone and Oestrogen - Oestrogen is responsible for secondary sexual characteristics in girls and together with progesterone it controls the menstrual cycle. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Peer reviewed

    The Journey of a cheese sandwich

    4 star(s)

    Proteins are vital for growth and to repair damaged areas of the human body. Hydrochloric acid is present in the stomach to kill bacteria. It has a low pH, and the enzymes produced by the stomach work best in acidic conditions.

  2. Investigating the effect of changing the concentration of an acid on the rate of ...

    I measured out the acid and water using a measuring cylinder that measures to the nearest cm3, so it is unlikely that I will be more than 1cm3 out. It is possible that I may have misread the side, thinking that the bottom of the meniscus was exactly on the mark, but it was actually slightly above or below it.

  1. See the effects of amylase on starch at different temperatures and to find at ...

    20�C 30�C 40�C 50�C 60�C Method: 1. Collect apparatus. 2. Get two test tubes and put 6ml starch in one and 4ml amylase in another. Put these in the water bath at 30�C. 3. While the amylase and starch are in the water bath, fill the five spotting tiles with two drops of iodine in each well.

  2. The Nervous System

    spinal cord Interconnect the sensory neuron with appropriate motor neuron Conduct impulse to an effector (muscle or gland) Axons Dendrites * Take information away from the cell body * Smooth Surface * Generally only 1 axon per cell * No ribosomes * Can have myelin * Branch further from the

  1. To investigate the factors that effect osmosis in living tissue.

    an indirect method of working out it's structure based on it's physicochemical properties. There have been two major theories regarding the structure of the plasma membrane. The first, sometimes labelled the 'sandwich' theory, was put forward by J.F. Danielli and H.

  2. Osmosis is defined as 'the movement of water molecules from an area of high ...

    And there fore the weight should decrease, at least noticeable for us to notice. The difference between the water concentration in the potato and the 0.8 molar solution of sucrose is big, and the water in the potato should be transferred from the potato, through the permeable membrane, to the solution surrounding the potato.

  1. The Effect of Glucose Concentration on the Rate of Osmosis

    in the same conditions because the results may be different if the test tubes are kept in the light than being kept in the dark. � Use the same measurements scales every time to reduce the inaccuracy level. � Put all the test tubes in the same place to prevent

  2. mobiles phones and brain cancer

    The Report suggests that: 'As a general rule the Expert Group considers that children less than 16 years of age should be discouraged from using mobile phones.' Taken on 24/02/2008 from http://www.iegmp.org.uk/report/clarification.htm (first issued 16th June 2000) (2) This rule was put in place because of the worrying damage mobile phone radiation can to do a developing nervous system.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work