CSEC: Classifying Animals

See animations below:

CLICK HERE FOR: video on classifying animals

• click "play movie" which will take you through the distinguishing feature between the different phylum

CLICK HERE FOR: Word Wall

• click on each word to obtain a definition....this is just to make sure

CLICK HERE TO: start easy quiz

• Let's see if you learnt anything with this EASY quiz
• Click online quiz
• select correct answers

CLICK HERE TO: Start hard quiz

• So how about trying the hard quiz?

HAVE FUN!!!!!!

CAPE 2: Nitrogen Cycle

see animations below: 

CLICK HERE FOR: CSEC version of the nitrogen cycle

• learn the names of each step and what happens here

CLICK HERE FOR: steps in the nitrogen cycle

• note what happens in each step

Now practice drawing the cycle on your own

How did you with this simple version? 

Let's try  drawing option number 2

How did you do with this one?

Let's wrap it up with a complete cycle

Microbes are involved at most stages of the nitrogen cycle:

Nitrogen Fixation. 78% of the atmosphere is nitrogen gas (N₂), but this is inert and can’t be used by plants or animals. Nitrogen fixing bacteria reduce nitrogen gas to ammonia (N₂ + 6H g 2NH₃), which dissolves to form ammonium ions (NH₄⁺ ). This process uses the enzyme nitrogenase and ATP as a source of energy. The nitrogen-fixing bacteria may be free-living in soil or water, or they may live in colonies inside the cells of root nodules of leguminous plants such as clover or peas. This is an example of mutualism as the plants gain a source of useful nitrogen from the bacteria, while the bacteria gain carbohydrates and protection from the plants. Nitrogen gas can also be fixed to ammonia by humans using the Haber process, and a small amount of nitrogen is fixed to nitrate by lightning.

Nitrification. Nitrifying bacteria can oxidise ammonia to nitrate in two stages: first forming nitrite ions NH₄⁺gNO^-₂  then forming nitrate ions NO^-₂gNO^-₃. These are chemosynthetic bacteria, which means they use the energy released by nitrification to live, instead of using respiration. Plants can only take up nitrogen in the form of nitrate.

Denitrification. The anaerobic denitrifying bacteria convert nitrate to N₂ and NO_x, which is then lost to the air. This represents a constant loss of “useful” nitrogen from soil, and explains why nitrogen fixation by the nitrifying bacteria and fertilisers are so important.

Ammonification. Microbial saprophytes break down proteins in detritus to form ammonia in two stages: first they digest proteins to amino acids using extracellular protease enzymes, then they remove the amino groups from amino acids using deaminase enzymes.

CAPE 1: CELL STRUCTURE & CELL MEMBRANE

Here are animations to help you grasp the concepts:

CLICK HERE FOR: cell anatomy

• pass mouse over cell organelles to view text on functions
• right click on the golgi apparatus and see how it works

CLICK HERE FOR: structure of the cell membrane

• click play

CLICK HERE FOR: water potential concept

• read text and play each animation

CLICK HERE FOR: calculating water potential 

• calculating water potential

CLICK HERE FOR: factors affecting water potential 

• factors affecting water potential 

CLICK HERE FOR: How diffusion works

• concept as you know it, look out for term concentration gradient 

CLICK HERE FOR: How osmosis works

• review the concept of osmosis as you know it with the introduction of of the term osmotic concentration

CLICK HERE FOR: Osmosis across cell membranes

• look out of key concepts such as: hypertonic, hypotonic, plasmolysis

CLICK HERE FOR: How Facilitated diffusion works

• introduction of term protein carrier

CLICK HERE FOR: sodium-potassium pump exchange

• note the role of ATP in the process
• note the role of the carrier proteins
• not the ratio and movement of sodium and potassium ions
• note change in conformation of carrier proteins

CLICK HERE FOR: How the sodium-potassium pump works

• cement concept learnt in previous video

P.S. WORK ON THE MCQ QUIZ BELOW EACH VIDEO 

Drawing Rules for Biological Drawings

Drawing Rules:

• Drawings should be done on plain paper (without lines) only.

• Paper should be bordered 1 cm form the margin at all for sides.

• Only sharp pencils should be used on your drawing paper (NO PEN).

• Each drawing should have a title which is to be written in CAPITAL letters and can be place at the bottom of the paper. 
It should begin as follows eg. DRAWING OF A _______________.

• Each drawing must have a magnification; this will give you the comparative size of your drawing to that of the original specimen. It can be calculated as follows
Magnification = length of drawing / length of specimen
The figure is always to 2 decimal places. Eg. Mg X 0.53 (no units required)

• Both the title and magnification should be singly underlined with the exception of Scientific names which will double underlined and written using the rules for written scientific names.

• Drawings should be large, clean and clear and to one side of the paper this is to accommodate labels.

• Smooth continuous lines should be use, no sketching or double lines allowed.

• Label lines should be drawn with a straight edge and should be parallel to each other (they should never cross), they should all end at the same place on the page.

• Labels should be to one side of the drawing (no arrow heads at the end if label lines)

• Labels should be written with pencil in lower case script

• No shading allowed instead you are allowed to stipple (use dots) or dashes (-) or lines to show contrast

Thanks to drawitneat for the diagrams

Rules for drawing graphs

Rules for drawing graphs 

 Ø  Graphs must be done on graph paper using only a pencil.

 Ø  All writing on graph paper must be done in script.

 Ø  Pencil should be pointed so that lines drawn are thin and accurately placed.

 Ø  All graphs must have a title eg. Bar graph showing________________

 Ø  Each axis must be appropriately labelled with graduations, what these graduations represent  as well as the related units.

 Ø  The scale of each axis must be clearly placed on the graph paper.

 Ø  When needed symbols to be used to identify strategic points must include `+’ (a cross not an` x’),● (a dot), (a dot with a surrounding circle)

 Ø  Broken or unbroken lines can be used to differentiate graphs on the same graph paper. 

 Ø  If a key is necessary, one must be included.

When plotting a graph the:-  independent variable goes on the horizontal axis  dependent variable goes on the vertical axis

CAPE 1 - CELLS and CELL STRUCTURE

When you look at animal or plant cells under the electron microscope, you can see a lot more detail. You are able to see the inside structures – organelles – of the cells, which together make a cell’s ultrastructure. Most organelles are common to both animal and plant cells. They have the same function in teach type of cell. Each organelle has its own specific role within the cell, all working together and each contributing towards the survival of the cell. This process is called division of labour.

CYTOSKELETON 

Cells contain a network of fibres made of protein. These fibres keep the cell’s shape stable by providing an internal framework called the cytoskeleton:
-->Some of the fibres, called  microfilaments (made of actin filaments) are able to move against each other – these cause the movement seen in some white blood cells, and they move some organelles around inside cells.  Movement is side-to-side like a wind-shield wiper.
-->There are other fibres, called microtubules. These are cylinders about 25nm in diameter made of a protein called tubulin, and may be used to move a microorganism through a liquid or to waft a liquid past a cell. Movement is circular like a helicopter propeller.

Comparing Micortubule & Microfilaments:

Arrangement of microtubules- arranged in a 9+2 arrangement seen below:

UNDULIPODIA & CILIA

Structurally, flagella of eukaryotes (correctly named undulipodia) and cilia are the same. Each one is made up of a cylinder than contains nine microtubules arranged in a circle and another two microtubules in a central bundle. Undulipodia are longer than cilia.
The undulipodium that forms the tail of a sperm cell can move the entire cell. Undulipodia and cilia can move because the microtubules can use energy produced by ATP (adenosine triphosphate).
Some bacteria have flagella. These look like the same as eukaryotic undulipodia, but their internal structure is different. These are true motors; they are made of a spiral of protein, called flagellin, attached by a hook to a protein disc at the base. Using energy from ATP, the disc rotates, spinning the flagellum
Cell ultrastructure and the importance of the cytoskeleton of cells.

M
any of the organelles found within cells are membrane-bound, this means that they have their own surrounding membranes to separate them from the rest of the contents of the cell. They have the same structure as the main cell membrane. The organelles form separate compartments within the cell, a process called compartmentalisation.

Structure	Function
The nucleus is the largest organelle in the cell. When stained, it shows darkened patches known as chromatin. It is surrounded by a nuclear envelope. This is a structure made of two membranes with fluid between them. A lot of holes, called nuclear pores, go right through the envelope. These holes are large enough for relatively large molecules to pass through. There is a dense, spherical structure, called the nucleolus, inside the nucleus	The nucleus stores the majority of the cell’s genetic material. The chromatin consists of DNA and proteins. It contains the instructions for making proteins. Some of these proteins regulate the cell’s activities. When a cell divides, chromatin condenses into visible chromosomes. The nucleolus makes RNA and ribosomes. These pass into the cytoplasm and proteins are assembled at them
Endoplasmic reticulum (ER) consists of a series of flattened membrane-bound sacs called cisternae. They are continuous with the outer nuclear membrane. Rough ER is studded with ribosomes, smooth ER does not have ribosomes	Rough ER transports proteins that were made on the attached ribosomes. Some of these proteins may be secreted from the cell. Some will be placed on the cell surface membrane. Smooth ER is involved in making the lipids that the cell needs
The Golgi apparatus is a stack of membrane-bound sacs, which looks very much like a pitta bread	The Golgi apparatus is responsible for receiving proteins and modifying them. It receives proteins from the ER and may add sugar molecules to them. It then packages the modified proteins into vesicles that can be transported. Some modified proteins go to the cell surface so they can be secreted
A single mitochondrion is spherical or sausage-shaped. It has two membranes separated by a fluid-filled space. The inner membrane is highly-folded to form cristae. The central part of the mitochondrion is the matrix	Mitochondria are the site where ATP is produced during respiration.  ATP is sometimes called the universal carrier energy as it drives most of the cellular processes
Chloroplasts are only found in plant cells, and have two membranes separated by a fluid-filled space. The inner membrane is continuous, with an elaborate network of flattened membrane sacs called thylakoids. A stack of thylakoids is a granum (plural: grana). Chlorophyll molecules are present on the thylakoids membranes and in the intergranal membranes	These are the site of photosynthesis in plant cells. Light energy is used to drive the reactions, in which carbohydrate molecules are made from carbon dioxide and water
A lysosome is a spherical sac surrounded by a single membrane	These contain powerful digestive enzymes which are there to break down materials. For example, white blood cell lysosomes help to break down invading microorganisms; and the specialised lysosome in the head of a sperm cell helps penetrate the female egg cell

►Golgi apparatus

◄The nucleus and endoplasmic reticulum

                                                                                  

    

◄Mitochondrion                ► Chloroplast

 

There are some organelles which are non membrane-bound…

Structure	Function
A ribosome is a tiny organelle that consists of two subunits. They can be found in the cytoplasm or attached to the ER making rough ER	Ribosomes are the site of protein synthesis in the cell (where new proteins are made). They act as an assembly line where coded information (mRNA) from the nucleus is used to assemble proteins from amino acids
Centrioles are small tubes of protein fibres (microtubules) which are present only in animal cells and cells of some protoctists. They are found in a pair next to the nucleus	These are used in cell division, they form fibres known as spindle which move the chromosomes during nuclear division

CAPE 2 & CSEC - Nutrient Cycles - Carbon & Nitrogen cycle

Nutrient Cycles

• Elements are taken up by producers (plants) / stored as organic matter
• Passed on across trophic level / consumer digest and absorb food / stored as organic matter
• Decomposers decay detritus and excretory products / return inorganic ions to environment / taken up by producers
• Warm temp / higher enzyme activity / faster decomposition

Table 9-14-1: Use of nutrients in plants and animals

PLANTS	ANIMALS
CARBON	Organic substances / lipids / proteins / ATP / chlorophyll	Organic substances / lipids / proteins / ATP / chlorophyll
NITROGEN	- Amino acid / nucleotide synthesise - In RNA, DNA, proteins, ATP	- Amino acid / nucleotide synthesise - In RNA, DNA, proteins, ATP
IRON	- In cytochromes / ETC - Needed for enzymes such as catalase to work - Synthesis of chlorophyll	- In cytochromes / ETC - Needed for enzymes such as catalase to work - Part of Hb
IODINE		Contained in thyroxine (hormone)
MOLYBDENUM	Nitrate reductase / reduces nitrates during synthesis of amino acids

Carbon Cycle

• Producers, consumers, decomposers
  • Add CO2 to the air by respiration
  • Carbon is stored in tissues as organic matter (carbohydrates, lipids, proteins)
  • Carbon is passed along food web by feeding
• Plants remove CO2 from air by photosynthesis
• Animals excrete carbon as waste products
• Decomposers decay detritus and excretory products / add carbon to soil
  • Detrivores digest detritus to small pieces / large surface area
  • Saprophytes digest smaller detritus by
    • Extracellular digestion by secreting enzymes
    • Absorb resulting nutrients across plasma membrane
    • Releases inorganic matter (CO2, H2O, mineral ions) into soil
• Fossil fuels
  • Combustion releases CO2 into air
  • Fossilisation of carbon atoms in organic compounds in dead remains (plants, animals) and excretory products (animals)
• Respiring organisms must not die to release stored carbon / differs from other cycles

Respiration, Photosynthesis and CO2

• Photosynthesis takes up more CO2 than is released by respiration
• CO2 concentration
  • Higher at night than at daylight; light-dependent reaction cannot take place
  • Peaks at winter time due to high oil consumption; low rate of photosynthesis due to cooler temp, shorter day length, loss of leaves
• Variation in a graph due to wind mixing CO2 with the surrounding air
  • Graph should show conc over whole area rather over a specific area
• Rate of photosynthesis and respiration are balanced in a rain forest
  • Forests grow for a long time and have stored lots of carbon in their tissues, other plants have stored carbon as cellulose and lignin
    
    
    

Nitrogen Cycle

• *processes involved in restoring nitrate conc in soil after cultivation is abandoned

1) Assimilation (→Building up organic molecules)

• Plants take up NITRATE NO3/AMMONIA NH3 from the soil by active transport
  • Used to synthesis amino acids / synthesise proteins / new cells and tissues
• Primary consumers feed on plants
  • Proteins are digested into amino acids and absorbed
  • Amino acids synthesise new proteins
• Nitrogen is passed along the trophic level through the food web

2) Ammonification*

• Detritus/leaves from plants/excretion from animals/dead animals
• Broken down by saprotrophs/decomposition
• Releases ammonia (NH3)/ammonium ions (from decay)
• Ammonia dissolves in H2O → NH3 + aq → NH4+

3) Nitrification*

• Ammonium NH4+ / nitrite NO2-
• Nitrite / nitrate
• By aerobic nitrifying bacteria eg. include: 
• (Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus - which are bacteria that convert ammonia to nitrites), 
• (Nitrobacter,Nitrospina, and Nitrococcus - which are bacteria that convert nitrites (toxic to plants) to nitrates )

4) Denitrification

• Removal of nitrogen from NO2 (nitrite)- and NO3 (nitrate)- to make N2(g)
• By anaerobic denitrifying bacteria eg. include:
•  Thiobacillus denitrificans, Micrococcus denitrificans, and some species of Serratia, Pseudomonas, and Achromobacter.  

5) Nitrogen Fixation*

• N2(g) is converted to nitrates by lightning N2(g) + O2 → NO3-
  • NITROGEN GAS IS CONVERTED TO NH3/NH4+
• By Haber process: N2(g) + H2 → ammonia NH3
  • //used to make fertilisers / added to soil / leakage of ions into river
• By Nitrogen-fixing bacteria by anaerobic nitrogenase. There are 2 types of nitrogen fixing bacteria:
• Live free in soil (non-symbiotic) bacteria, including the cyanobacteria (or blue-green algae) Anabaena, Azotobacter, Beijerinckia, and Clostridium;
•  Mutualistic (symbiotic) bacteria such as Rhizobium, living in the nodules of leguminous plants, and Spirillum lipoferum, associated with cereal grasses.