Biology Module 2

Cells, Tissues and Organs - 1.1 Animal and Plant Cells

Animal Cells

• Nucleus - To control cell's activities
• Cytoplasm - where chemical reactions take place
• Cell Membrane - controls the movement of materials in and out of the cell
• Mitochondria - where energy is released during aerobic respiration
• Ribosomes - where protein synthesis takes place

Plant (and Agal) Cells (as well as stuff in animal cells)

• Cell Wall - Made of cellulose, to support the cell
• Chloroplasts - contain chlorophyll for photosynthesis. These absorb light energy for food
• Permanent Vacuole - Containing cell sap. 

Cells, Tissues and Organs - 1.2 Bacteria and Yeast

Bacteria - 

• Bacteria cells have a cell membrane and a cell wall which surround cytoplasm. 
• Genetic Material is in the cytoplasm
• Bacterial colonies (a multitude of bacteria) can be seen with naked eye.

Yeast - 

• Single-celled organism 
• Nucleus, cytoplasm, cell wall and cell membrane 

Pretty much it. If you want look at diagrams on p40 

Cells, Tissues and Organs - 1.3 Specialised Cells

There isn't just one type of cell in animals and plants. All are specialised to do different jobs. 

• If a cell has multiple mitochondria then it requires a lot of energy e.g. muscle cell, sperm cell
• If a cell has many ribosomes it is making a lot of protein e.g. gland cells which produce enzymes
• Sperm cells need tails to move
• Receptor cells have special strucures which enable them to detect stimuli e.g. cone cells in the eye are light sensitive.
• Neurons are specialised to carry impulses to and from CNS
• Plant cells with multiple chloroplasts will be photosynthesising
• Root hair cells increase the surface area of the root so that it can absorb water and mineral ions efficiently.

These are all just example. cilia, wafting hairs ... 

Cells, Tissues and Organs - 1.4 Diffusion

 Diffusion - The spreading out of the particles of a gas or of any substance in a solution

Net Movement - This depends on the concentration of the particles on each side of the cell                                   membrane - going in or out of the cell. Because paricles move randomly there                            will be an overall movement from an area of high concentration to an area of                            low concentration. The larger the difference in concentration the faster the rate                          of diffusion.

Examples are - 

- the diffusion of oxygen into the blood cells during respiration. 

- the diffusion of carbon dioxide into actively photosynthesising plant cells

- the diffusion of simple sugars and amino acids from the gut through cell membranes.  

Cells, Tissues and Organs - 1.5 Tissues and Organs 

Tissues

A tissue is a group of cells all doing the same function.

Animal Tissues - Muscle tissues (contract to bring movement), Glandular tissues (produces                               enzymes and hormones), Epithelial tissue (covers parts of the body).

Plant Tissues- Epidermal tissue (covers the plant), Mesophyll (can photosynthesise), Xylem                           and Phloem tissue (transport substances around the plant).

Organs

These are made of tissues and perform vital functions necessary for living. The stomach requires the tissues muscular (to churn), glandular (to produce digestive enzymes) and epithelial (to cover outside and inside). 

Leaf, stem, and root are plant organs which contain Epidermal tissue, Mesophyll and Xylem Tissue and Phloem. 

Cells, Tissues and Organs - 1.6 Organ Systems

Food we eat must be changed from insoluble molecules to soluble, only then can it be absorbed into the blood. The digestive system does this.

• Glands such as the pancreas and salivary glands which produce digestive juices
• Stomach and small intestine where digestion occurs
• Liver which produces bile
• Small intestine where the absorption of soluble food occurs
• The large intestine where water is absorbed from indigested food and the rest turned into poo-poo. 

Okay mate onto the next one, you can do it ...

Organisms in the Environment - 2.1 Photosynthesis

This can only be carried out by green plants and algae. It occurs due to chlorophyll in chloroplasts which absorbs the Sun's energy.

Caarbon Dioxide + Water (+ light energy) = Glucose + Oxygen

• Carbon Dioxide is taken in by the leaves and water is taken up by the roots
• The chlorophyll traps light energy needed for photosynthesis
• This energy is used to convert the carbon dioxide and water into glucose.

Oxygen is released as a by-produc of photosynthesis.

Some of the glucose is converted into insoluble starch for storage.

Iodine Test

Testing leaves with Iodine Solution we can identify any starch in the leaf, thus showing photosynthesis has occured. Only green patches will turn navy - shows that starch has been made. Variagated leaves have green and white patches. 

Organisms in the Environment - 2.2 Limiting Factors

Anything which decreases the rate of Photosynthesis is a Limiting Factor. These three are Limiting Factors

• Light Intensity
• A lack would slow down the rate of photosynthesis as light provides energy. Light can be limited on sunny days by trees. 
• Temperature
• Enzymes don't work efficiently in too cold conditions and so this will slow down the rate of photosynthesis
• Carbon Dioxide Concentration
• The rate will slow down if low levels. Carbon Dioxide can be limited in an enclosed space e.g greenhouse on a sunny day.

Independant Variable - The one being tested

Dependant Variable - The one you measure. 

Organisms in the Environment - 2.3 How Plants Use Glucose

Uses of Soluble Glucose - 

• Converted into Insolluble Starch for storage
• Used for respiration
• Converted into fats and oils for storage
• Used to produce cellulose which strengthens cell walls
• Used to produce proteins

Plant and algal cells also need a supply of mineral ions such as nitrate ions in order to produce protein. Plants absorb nitratee ions from the soil. Algae absorb nitrate ion from the water they live in. 

Organisms in the Environment - 2.4 Making the Most of Photosynthesis

We can control the environment to give plants the best conditions for growth.

Greenhouses and polytunnels can be constructed to grow plants in an enclosed space. If the greenhouse has heaters and lamps the rate of photosynthesis will increase but may stop if one of the limiting factors is too high. By adding Carbon Dioxide we ensure the rate also increases this way. We can add extra minerals to the soil for healthy growth (Nitrate ions)

This can all be expensive so the grower has to evaluate the overall cost and its worth and compare the biomass of plants grown indoors and outdoors without these factors. 

Organisms in the Environment - 2.5 Organisms in their Environment

Living organisms form communities. Relationships within these communities can be disturbed by physical factors such as

• Temperature - e.g arctic plants are small which limits the number of plant eaters which can survive in the area
• Availability of Nutrients - Most plants struggle to grow when mineral ions are in short supply. This causes fewer animals in that area.
• Amount of Light - Shaded plants often have broader leaves or more chlorophyll. Plants won't grow in areas of limited light.
• Availability of Water - Plants cannot grow without water. This limits the amount of animals in the environment. 
• Availability of Oxygen and Carbon Dioxide - All plants need Carbon dioxide so lack of will mean fewer plants for animals. Water invertebrates can live at low levels of oxygen but most fish need high levels. 

Organisms in the Environment - 2.6 Measuring the Distribution of Organisms

Quantative data (look up definition on p47) can be obtained by:

• Random quantative sampling using a quadrat
• Sampling along a transect

Quadrat

A square wooden fram which can be split into a grid. If several are placed in field, an investigator cann count the number of a particular type of animal or plant. The result can be estimated for the entire field. 

•  A line is marked between two points e.g. from top of shore to sea bed
• A quadrat can be placed every five metres along the line and the organisms counted.
• Physical factors can also be measured at each quadrat placement. 
• This is taking a transect
• Sample Size - This is important because the result must be representative of the whole area. Enough must be done to make sure it is representative. 

Organisms in the Environment - 2.7 How Valid is the data?

Not all variables can be controlled making investigations of organism distribution in an environment difficult. 

If a transect of a beach is done in the morning, then it must be compared with transect of the smae spot at the same time but a month later. The time of day would be a control variable. 

A measurement is repeatable if the investigator can repeat the experiment exactly and get the same results. However since he could be making the same mistakes it is also necessary to check the results ensure they are reproducible. This happens if another investigator or different methods/techniques can repeat the experiment and obtain the same results. 

Sample size is important to obtain valid, repeatable and reproducible results. If the sample is too small it may not be representative. The larger the sample size the more trust worthy it is. 

Enzymes - 3.1 Proteins, Catalysts and Enzymes

Proteins

• Molecules are made of long strands of amino acids
• Long chains are folded to produce specific shapes
• They can be - structural components of tissues (muscle), hormones, antibodies and catalysts. 

Enzymes

• Control chemical reactions in cells.
• They are biological catalysts.
• Enzymes are large proteins and the shape has an active site - where the molecules can fit. 
• The substrate in a reaction can be held in the active site and either be connected to another molecule or be broken down. 
• Enzymes can build large molecules from smaller ones (building starch from glucose), change one type of molecule into another (sugar into another type), break down large molecules into smaller ones (the digestive system). 

Enzymes - 3.2 Factors Affecting Enzyme Action

Enzyme reactons are like other reactions.

• The rate of reaction is increased with temperature. Higher temperatures cause the molecules to move around faster and collide more frequently and with more energy. 
• Too high temperature and the enzymes denature due to the active site changing shape. 
• Each enzyme works best at a particulaar pH value. 
• If the pH is too acidic or alkaline then the active site could change shape. Then the enzyme becomes denatured. 

Enzymes - 3.3 Enzymes in Digestion

Some enzymes work outside of cells. Digestive are produced by specialised cells in glands and the lining of the gut. Digestion involves the breakdown of large insoluble molecules into smaller soluble molecules which can be absorbed. 

Amylase

A Carbohydrase. Produced in slaivary glands, the pancreas and the small intestine. Amylase catalyses the digestion of starch into sugars in the mouth and small inestine. 

Protease

Produced by the stomach, the pancreas and the small intestine. Catalyses the break down of proteins into amino acids in the stomach and small intestine. 

Lipase

Produced by the pancreas and small intestine. Catalyses the breakdown of lipids (fats and oils) to fatty acids and glycerol. 

Enzymes - 3.4 Speeding Up Digestion

POrotease work best in acidic conditions. Glands in  stomach wall produce hydorchloric acid to create very acidic conditions.

Amylase and Lipase work in the small intestine. They work best when the conditions are slightly alkaline. 

Bile

The liver produces it but it is stored in the Gall bladder. The alkaline bile is squirted into the small intestine and neutralises stomach acid. Bile makes the conditions in the small intestine slightly alkaline. It can break down large insoluble fat molecules into small insoluble molecules but it can't digest fats. 

Enzymes - 3.5 Making Use of Enzymes

Enzymes can be used in industry but they are costly to produce. They are obtained from micro-organisms which produce them but then pass them out of their cells. Enzymes can bring about reactions at normal temperatures and pressures (unlike chemical reactions). THey can also be re-used.

Biological Detergents

Contain proteases and lipases to digest food stains on clothes. These work at lower temperatures than normal washing powders, thus lowering energy costs.

• Some enzymes are used in baby food e.g proteins. This makes digestion for a baby easier.

Isomerase

This converts glucose into fructose syrup. Fructose is much sweeter so less is needed in foods to make it taste good, therefore the food is less fattening. 

• Carbohydrases are used to convert starch into sugar syrups for use in foods. 

Enzymes - 3.6 High-tech Enzymes

Advantages

• Biological washing powders containing enzymes are very effective
• Biological washing powders can be used at lower temperatures
• Some enzyms are used in medicine to diagnose, control or even cure disease
• In industry costs of equipment and energy can be reduced

Disadvantages

• I people misuse washing powder they may have allergic reactions on their skin. The enzymes are enclosed in capsules in the dry powder. Once the powder is dissolved, hands can't be placed in the water. 
• Enzymes may enter waterways via sewage system
• Industrial enzymes are costly to produce
• Enzymes denature at the high temperatures needed to kill pathogens
• Some fabrics (wool) will be digested by proteases.

Energy from Respiration - 4.1 Aerobic Respiration

This takes place continually in plants and animals. The process usees glucose and oxygen to release energy and carbon dioxide and water are waste products. Most of the chemical reactions take place in the Mitochondria and are controleld by enzymes

Glucose + Oxygen = Carbon Dionxide + Water (+ energy)

Energy released may be used as 

• build larger molecules from smaller ones
• enable muscle contraction
• maintain a constant body temperature
• Build sugars, nitrates and other nutrients into amino acids and then proteins in plants.

Tests fro respiration involve turning Limewater cloudy to show Carbon Dioxide is being produced. 

Energy from Respiration - 4.2 The Effect of Exercise on the Body

When you exercise your muscles need more energy to contract. 

This means that you need to increase the intake of oxygen and glucose that reach the muscles for aerobic respiration, you also need to remove carbon dioxide faster. 

To do this the heart rate increases and blood vessels transporting oxygen dilate to allow more. Your breathing rate and the depth of each breath increase to allow a greater uptake of oxygen and release of carbon dioxide. 

Muscles store glucose as glycogen, this can be converted back to glucose during exercise. 

Lack of oxygen will cause Anaerobic respiration and an increase in Lactic acid. 

Energy from Respiration - 4.3 Anaerobic Respiration

During exercise if there is an insufficient amount of oxygen, then the body will start to respire anaerobically. This means that there is fewer energy supplied to the muscles and there is also an increase of Lactic Acid (by-product of Anaerobic respiration) in the blood. 

Since glucose is not completely broken down, there is a decrease in energy given off. Lactic Acid build up causes muscle fatigue, but this can be removed by blood flowing throug the muscles. 

Anaerobic respiraton only happens after long periods of exercise

Oxygen Debt

Lactic Acid causes muscle fatigue. When the exercise has finished, this acid must be completely broken down. You still need to take in a lot of oxygen to do this. THe extra oxygen is known as the 'oxygen debt'. Eventualyl the oxygen oxidises lactic acid into Carbon dioxide and water. 

Simple Inheritance in Animals and Plants - 5.1 Cell Division and Growth

Cell division is necessary for growth and repair of damaged tissues.  

Mitosis

• Asexual reproduction. Partner is not required. 
• Results in two identical copies (clones) of the original cell.
• A copy of each chromosome (genes) is made before the cell divides and one of each set goes to one of the two produced cells. 
• In early development of animal and plant embryos the cells are unspecialised. 
• Cells of offspring produced asexually are produced by mitosis from the parent cell. They contain the same alleles (genes) as the parent.

Most animals differentiate early in development and cell division is mainly for growth and repair. 

Simple Inheritance in Animals and Plants - 5.2 Cell Division in Sexual Reproduction

Cells in reproductive organs (testes and ovaries) divid by Meiosis to form sex cells (gametes), human gametes are the sperm and ova. 

Each gamete has only one chromosome from the original pair. All cells are individual from parents and themselves. Sexual reproduction results in variation as the gametes fuse. Half come from the mother, half come from the father. When gametes join (fertilisation) a single body cell with new pairs of chromosomes is formed. Humans have 23 pairs (46).

A new individual then develops by this cell repeatedly dividing by Mitosis. 

So humans perform Meiosis to fuse the cell. Mitosis is then done to multiply the parent cell. 

Meiosis

• A copy of each chromosome if made
• The cell now divides twice to form foour gametes (sex cells).
• Each gamete has a single set of chromosomes with a different combination of genes. 

Simple Inheritance in Animals and Plants - 5.3 Stem Cells

•  Unspecialised cells
• Found in the human embryo and in adult bone marrow
• Change into other types of body cell (differentiation)
• Layers of cells in the embryo differentiate into all the cells the body needs
• Stem cells in adult bone marrow can change into other types of cell
• It is hoped that stem cells can be used to treat conditions such as paralysis and so on. 
• Considered by some to be unethical 

Pretty much it. 

Simple Inheritance in Animals and Plants - 5.4 From Mendel to DNA

Gregor Mendel 

• First one to suggest how characteristics were inherited. (Monk)
• Suggested the idea of separately inherited 'factors'
• Long time for Mendel's ideas to be accepted because scientists did not know about genes and chromosomes until after Mendel died. 
• The 'factors' are now known as genes. These are found in Chromosomes

Chromosomes are made of DNA which is a very long molecule with a double helix structure. Genes are short sections of DNA. Every individual (except identical twins) has different DNA. This unique DNA pattern can be used to identify people by their DNA fingerprint. 

Genetic Code

• Each gene codes for a particular combination of amino acids which make a specific protein. The weird work sheet where it was like 2 4 7 11 6 3 etc. 

Simple Inheritance in Animals and Plants - 5.5 Inheritance in Action

Human beings have 23 pairs of chromosomes (46), one pair are the sex chromosomes.

Human females = two x chromosomes (**)

Human Males = one X, one Y chromosome (XY)

Genes controlling the same characteristic  called Alleles. If an allele 'masks' the effect of another it is said to be DOMINANT. The allele where the affec is 'masked' is called RECESSIVE. Gnetic diagrams illustrate how alleles and characteristics are inherited. 

Genetic Terms and Models

Phenotype - Physical appearance of the characteristic (e.g dimples)

Genotype - the genetic makeup. What alleles does the individual inherit. DD, Dd or dd. 

Homozygous - both alleles are the same DD (Homozygous dominant) or dd (homozygous                               recessive).

Heterozygous - the two alleles are different Dd. 

Simple Inheritance in Animals and Plants - 5.6 Inherited Conditions in Humans

Genetic Disorders (many of them) can be caused by either a Dominant or a Recessive allele. 

If the allele is dominant the offspring only has to inherit 1 dominant allele to have the genetic disorder. Polydactyly is caused by a DOMINANT allele. Born with multiple fingers/toes.

If an allele is recessive, the offspring only has to inherit 2 of the recessive allele to have the genetic disorder. Cystic Fibrosis is caused by a RECESSIVE allele. Causes produciton of thick sticky mucus from cell membranes, this effecs the organs including lungs and pancreas. 

A child must inherit a recessive allele from both parents to develop cystic fibrosis. Both parents don't have to have the disease they can just be carriers of it. 

Simple Inheritance in Animals and Plants - 5.7 Stem Cells and Embryos - science and ethics

• Adult stem cells can treat leukaemia. 
• Embryonic cells (taken from IVF or created from adult cells or taken from the umbilical cord)  could be used to grow new tissues and organs for transplant. 
• Since research is experimental, some are concerned. Concern is also rife about the embryos having the potential to be babies and are destroyed, the embryo cannot give permission and the research is expensive. 
• Embryo screening involes test to diagnose disorders before the baby is born 
• This can help the parents decide if they want the pregnancy terminating so the baby does not have a disadvantaged life. 
• In IVF only healthy embryos are screened and placed back into the mother. Embryos with faulty genes are destroyed and many think this is unethical. 

Old and New Species - 6.1 The Origins of Life on Earth

It is believed that Earth is 4500 million yers old. And life began 3500 million years ago. We can date rocks, fossils are found in rocks so we can date when different organisms existed. Fossils can be formed by - 

• From the hard parts of animals which do not decay easily
• From parts of organisms that have not decayed because of some of the conditions for decay are absent
• when parts of the roganism are replaced by other materials such as minerals as they decay
• as preserved traces of organisms

Most organisms that die, did not leave a fossil because the conditions for it were not present. 

Many life forms had soft bodies so were not likely to fossilize

Traces which were left could have been destroyed by earthquakes, volcanoes or geothermal activity. 

Old and New Species - 6.2 Exploring the Fossil Evidence

The fossil record is incomplete but we can learn a lot from existing ones. Some organisms have evolved a lot, others not so much. 

Extinction - a species that once existed has died out e.g mammoth, dodo bird, sabre-tooth tiger.                    It can be caused by the following - 

• A new disease may kill all members of a species
• The environment changes over geological time
• New diseases may be introduced
• A new predator may evolve or be introduced to an area that effectively kills and eats all of a species
• A new competitor may evolve or be introduced to an area. The original would be left with little to survive on
• A single catastrophic even may occur which destroys the habitat e.g. a super volcano eruption
• Natural changes in species occur over time. 

Old and New Species - 6.3 More About Extinction

biggest influences on survival are environmental changes. CLiamte change is an important influence i ndetermining which species survive. A species which is very wel ladapted to a hot climate may become extinct in an Ice Age. It could be there is insufficient food or it is too cold to breed. 

• Climate Change can make it too hot or cold, wet or dry to allow a species to live
• Fossil Evidence shows there have been mass extinctions on a global scale. Many species died out over several mllion years (a short amout of time) =. This can be due to rapid climate change caused by a meteorite collision with Earth or a catastrophic natural disaster. 
• Dinosaur extinction has puzzled scientists.
• 1) Collision of a giant asteroid with Earth caused huge fires, earthquakes, landslides and tsunamis. The dust which rose masked the sun causing darkness and lower temperatures. Plants could not grow and temperatures fell. 
• 2) The extinction was a slow process due to sea ice melting and cooling the sea temperature by 9 degrees C, therefore there was less plankton = less food.

Old and New Species - 6.3 More About Extinction

biggest influences on survival are environmental changes. CLiamte change is an important influence i ndetermining which species survive. A species which is very wel ladapted to a hot climate may become extinct in an Ice Age. It could be there is insufficient food or it is too cold to breed. 

• Climate Change can make it too hot or cold, wet or dry to allow a species to live
• Fossil Evidence shows there have been mass extinctions on a global scale. Many species died out over several mllion years (a short amout of time) =. This can be due to rapid climate change caused by a meteorite collision with Earth or a catastrophic natural disaster. 
• Dinosaur extinction has puzzled scientists.
• 1) Collision of a giant asteroid with Earth caused huge fires, earthquakes, landslides and tsunamis. The dust which rose masked the sun causing darkness and lower temperatures. Plants could not grow and temperatures fell. 
• 2) The extinction was a slow process due to sea ice melting and cooling the sea temperature by 9 degrees C, therefore there was less plankton = less food.

Old and New Species - 6.4 Isolation and the Evolution of New Species

New species can arise from existing species if a group becomes isolated from the rest. 

Geographical Isolation - where an island separates a species from the mainland or if a new river                                       separates two areas. Natural evolution will occur between the isolated                                         group. Natura lselection will occur but different characteristics will suit the                                   two types of the species better due to the difference in conditions. If the                                       populations are brought back together after tiema dn cannot interbreed we                                   say they are two new species. 

Speciation

This has occured when the two groups can no longer interbreed. The process is 

Isolation (probably Geographical) - Genetic Variation - Alleles Selected (Natural Selection) - Interbreeding no longer possible - New species (speciation) 

Module 2 finished!!!!!!!!!!!!!

Old and New Species - 6.4 Isolation and the Evolution of New Species

New species can arise from existing species if a group becomes isolated from the rest. 

Geographical Isolation - where an island separates a species from the mainland or if a new river                                    separates two areas. Natural evolution will occur between the isolated                                      group. Natura lselection will occur but different characteristics will suit                                    the two types of the species better due to the difference in conditions.                                    If the populations are brought back together after tiema dn cannot                                            interbreed we say they are two new species. 

Speciation

This has occured when the two groups can no longer interbreed. The process is 

Isolation (probably Geographical) - Genetic Variation - Alleles Selected (Natural Selection) - Interbreeding no longer possible - New species (speciation) 

Module 2 finished!!!!!!!!!!!!!