Biology double-award

Section 1: The Nature & Variety of Living Organisms

a) Characteristics of Living organisms

1.1-Understand that living organisms share basic characteristics.

-They require nutrition (eating food)

-They respire

-They excrete their waste

-They respond to their surroundings (response to stimuli)

-They move

-They control their internal conditions (maintain homeostasis)

-They reproduce (produce offspring)

-They grow & develop

1.2- Describe the common features shared by organisms within the following main groups: plants, animals, fungi, bacteria, protoctists and viruses, and for each group describe examples of their features (details of life cycle and economic importance are not required)

Plants: Multicellular organisms; cells contain chloroplast & are able to carry out photosynthesis; their cells have cellulose cell walls; store carbohydrates as sucrose or starch.

Examples: Flowering plants (cereal) (e.g. maize), and herbaceous legume (e.g. peas or beans)

Animals: Multicellular organisms; cells don’t contain chloroplast & cannot carry out photosynthesis; no cell wall; usually have nervous coordination and are able to move from one place to another; carbohydrates stored as glycogen.

Examples: Mammals (e.g. humans & bears) and insects (e.g. housefly & mosquito)

Fungi: Organisms that cannot carryout photosynthesis; body is organized into a mycelium (made from a thread like structure called hyphae, which contain many nuclei); some examples are single-celled; their cells have cells have walls made of chitin; they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products; this is known as saprotrophic nutrition; they may store carbohydrates as glycogen.

Examples: Mucor (typical fungal structure) and yeast (single-celled)

Bacteria: Microscopic single-celled organisms; contain a cell wall, cell membrane, cytoplasm and plasmids; no nucleus but contain a circular chromosome of DNA; some bacteria can carry out photosynthesis but most feed off other living or dead organisms.

Examples: Lactobacillus bulgaricus (rod shaped bacteria used in the production of yoghurt from milk) and Pneumococcus (a spherical bacterium that acts as the pathogen causing pneumonia)

Protoctists: Microscopic single-celled organisms

Example: Amoeba (live in pond water have features like animal cells) and Chlorella (have chloroplasts and are more like plant cells) a pathogenic (the mechanism that causes the disease) example is Plasmodium (causes malaria)

Viruses: small particles; parasitic and can reproduce inside living cells; infect every type of living organism. They have a wide variety of shapes and sizes; no cellular structure but have a protein coat and contain on type of nucleic acid (DNA or RNA)

Example: Tobacco Mosaic virus (causing discoloring of the leaves of tobacco plants by preventing the formation of chloroplast) the influenza virus (causes flu) and the HIV virus (causes AIDS)

1.3-Recall the term  ‘pathogen’ and know what pathogens may be fungi, bacteria, protoctists or viruses.

A pathogen is a microorganism that can cause a disease. They may be Fungi, Bacteria, Protoctists or viruses

Section 2: Structure & Functions in Living Organisms

a) Levels of Organization

2.1-Describe the Levels of organization within organisms: organelles, cells, tissues, organs and systems.

Organelles: membrane-bound structures found in the cytoplasm of a cell that carries out a particular function in the cell.

Cell: is the basic unit of all living things. All living things are made up of one or more cells that specialize to carry out a specific function in the body - e.g. sperm cells, nerve cells, and palisade cells in a leaf.

Tissue: Is a group of cells that preform the same function. A tissue carries out a specific function – e.g. muscle tissue and nerve tissue and palisade tissue in a leaf.

Organ: Several types of tissues working together. Organs carry out specific functions – e.g. a stomach is made of muscle tissue, nerve tissue, connective tissue and others; a leaf has palisade tissue, epidermal tissue, spongy tissue, and others.

System: Organs grouped together to carry out a major life function.  –e.g. Stomach and intestines are part of the digestive system. The flowers contain the organs of the plants reproductive system (anther, ovary…)

b) Cell Structure

2.2-Describe the cell structures, including the nucleus, cytoplasm, cell membrane, cell wall, chloroplast and vacuole.

*Both cells contain mitochondria it is in the cytoplasm

2.3-Describe the functions of the nucleus, cytoplasm, cell   membrane, cell wall, chloroplast and vacuole.

2.4- Compare the structures of plant and animal cells.

c) Biological molecules

2.5- Identify the chemical elements present in carbohydrates, proteins and lipids (fats and oils)

-Carbohydrates, Proteins and Lipids are known as macromolecules. They are all made up of elements:

2.6- Describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugar; protein from amino acids; lipid from fatty acids and glycerol.

-Carbohydrates, Proteins and Lipids are known as macromolecules. Which means that they are made up from smaller basic units known as monomers.

2.7- Describe tests for glucose and starch

Testing for Starch:

-Starch can be detected by the iodine test:

1.) Add a few drops of iodine to the solution

2.) If the solution has turned blue-black it is a positive test for starch

3.) If there is no starch the solution will stay a redy-brown color

Testing for Glucose:

-Benedict's solution (blue) contains copper (II) sulphate.

-Sugars such as glucose, maltose, fructose and lactose can reduce the copper (II) in Benedict's solution to copper (I).

-Producing a brick-red precipitate of copper (I) oxide when boiled with Benedict's solution:

1.) Add Benedict's solution to glucose solution in a test tube and shake the mixture. Leave the test tube in a beaker of boiling water for a while

2.) If the solution has turned into a orange-red precipitant it is a positive test for glucose

3.) If there is no glucose the solution will stay blue

2.8- Understand the role of enzymes as biological catalyst in metabolic reactions.

Enzymes lower the activation energy of a reaction- making it faster- and they are unchanged from beginning to end of a reaction. These two things mean its a catalyst.

2.9- Understand how the functions of enzymes can be affected by changes in temperature, including changes due to change in the active site.

-The shape of the active site depends on the shape of the protein molecule. Temperature and pH affect this shape.

-Enzymes are specific to each type of molecule and work the same way a key fits a lock

-Enzymes will break (denature), if the temperature is too low enzymes work slowly

-Enzymes are proteins that can join or separate other molecules

-Anything that changes the shape of the active site stops the enzyme working (denatures the enzyme).

2.11- Describe experiments to investigate how enzyme activity can be affected by changes in temperature.

You can investigate the effect of temperature on the enzyme amylase using starch and iodine, putting the mixture in water baths at different temperatures.

d) Movement of substances into and out of cells

2.12- Understand the definitions of diffusion, osmosis and active transport.

Diffusion: The passive transport of substances other than water through a cell membrane. Molecules move from an area of high concentration to an area of low concentration. The random movement of molecules across the cell membrane never stops, even after equilibrium is reached.

Osmosis: The passive transport of water molecules through a cell membrane. Molecules move from an area of high concentration to low concentration.

Active Transport: The movement of particles from an area of low concentration to high concentration through a partially permeable membrane. (Uses energy)

2.13- Understand that movement of substances into and out of cells can be by diffusion, osmosis and active transport.

The movement in and out of cells can be by diffusion, osmosis and active transport.

2.15- Understand the factors that affect the rate of movement of substances into and out of the cells, to include the effects of surface area to volume ratio, temperature and concentration gradient

-The greater the difference between the areas of high and low concentration, the faster the diffusion will occur.

-Higher temperatures means more kinetic energy making the molecules move faster, leading to higher diffusion rates.

-Higher surface areas to volume ratios will mean faster diffusion because there will be more space to diffuse in. Cells want a large surface area to volume ratio.

2.16- Describe experiments to investigate diffusion and osmosis using living and non-living systems.

You can demonstrate diffusion using agar blocks dyed with potassium permanganate.

You can demonstrate osmosis using membrane bags, by using potato tissue or by observing plant cells.

e) Nutrition

Flowering Plants:

2.17- Describe the process of photosynthesis and understand its importance in the conversion of light energy to chemical energy.

Plants are “phototrophic” (generate their own food using energy from the sun). They do this through, photosynthesis, which is the process in which light energy is converted into chemical energy.