Biology Module 2 - Lecture notes for 1,2,3,4 periods PDF

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Lecture notes for 1,2,3,4 periods
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Biology Module 2 Unicellular, Colonial & Multicellular Life-Forms Unicellular Living Things  Most of the individual living things on Earth are composed of a single, living cell. To survive as a single-celled organism, the cell must be capable of carrying out ALL the functions necessary...feeding, moving about reproducing, etc.  Eg. Bacteria, with a high surface area to volume ratio unicellular organism it can survive at diverse conditions as opposed to multicellular organisms which would diminish. Multicellular Living Things  Multicellular organisms are composed of many different types of specialized cells. Combination of similar cells grouped together and perform specific functions that combine for an efficient work rate.  It is often a survival advantage for a living thing to be large. Larger organisms can gather more food (or other resources) from the environment. Large organisms deter predators, or can overwhelm their prey. They can dominate their “herd” and mate more often to produce more offspring Colonial Life-Forms 

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There are a variety of (generally unrelated) living things which are somewhere in-between the unicellular and multicellular states. Colonial organisms were the first evolutionary step from single-celled to multicellular organisms All the individual cells of a colonial organism can carry out all functions necessary for life, so they could all be seen as a single organism. Some colonial organism's individuals show a degree of differentiation and specialization

Multicellularity Cell Differentiation  Plants and animals are made of many cells, but each organism is not just a jumble of cells living and growing in a big lump. There is always an organized structure to the way their bodies are built.  Firstly, not all the cells in a multicellular organism are the same. They are differentiated into many shapes and sizes. Each cell type does a different “job” in the body, and has the shape, size and ability to match that function. For example...  Red blood cells – responsible for carrying oxygen around your body  Nerve cells (neurons) – responsible for sending signals around the body to control and coordinate your movements and bodily functions.  Every specialist cell type in a multicellular organism has features (size,shape, organelles,etc) which suit its function.  Structure has a close relationship to its function

Organization of multicellularity  Many cells working together form tissue. The cells involved are specialized to cooperate with each other to accomplish one common goal. There are many different types of tissue in both plants and animals.  When there are layers of tissue working together, they form an organ. All animals contain organs. In fact, mammals have five vital organs that they cannot live without: kidneys, lungs, liver, heart, and brain.  When organs work together, they form organ systems. Organ systems keep the body regulated and in a stable state. These systems often work together and rarely work in isolation

General characteristics Excitability -

The ability to receive and respond to a stimulus In skeletal muscle, the stimulus is a neurotransmitter ( chemical signal) release by a neuron ( nerve cell). In smooth muscle, the stimulus coud be a neurotransmitter , a hormone stretch, In cardiac muscle , the stimulus could be a neurotrasnmsitter , a hormonr , stretch.

Contractility -

The ability to shorten forcibility when adequately stimulated This is the defining property of muscle tissue

Extensibility -

The ability to be stretched ( extended)

Elasticity -

The ability to recoil and resume original length after beign stretched.

Functions - Movement - Locomotion - Matinains posture - Produces heat - Facial expxression - Pumps blood - Peristalisis 3 types of muscle tissue Cardiac muscle Skeletal muscle Smooth muscle Nerve tissues By far the most complex tissue in the human body is nerve tissue Formed by a network of more 100 million nerve cells, assisted by many more glibal cells. Each neuron has, on a average at least a thousand interconnection with other neurons forming a very complex nervous system. Functions Regulates and controls body functions Generates and transmits nerve impulses Supports insulates and protects impulse generating neurons. Gilal cells Glia carry nutirents speed repair provide myelin for axons support

Plant tissues There are four types of tissues In plants Dermal tissue     

also called the epidermis composed of flattened cells protects and covers the body of the plant produces the cuticle Located in the epidermal layer

Stomata:  opening in leaf tissue  help control water loss from plants Guard cells  Controls the opening and closing of stomata Trichomes  Hairlike projections on stem and leaf  Reduces evaporation of water and plant Vascular tissue  main function to transport water, food throughout the plant two types of vascular tissue - xylem  transport water from roots plant  composed of tracheids  tubular cells taperaed at each end Phloem  Transport sugars to all parts of the plant  Made up of tubular cells joined end to end

- ground tissue - meristematic tissue

Functions of leaves 1. 2. 3. 4. -

Photosynthesize Broad, flat surface increases area for light absorption Have systems to prevent water loss Stomata ope in day but close at night a0r when hot to conserve water Waxy cuticle on surface System of gas exhancge Allow CO2 if

N and O2 out a leaf B. Leaf structures 1. Cuticle: waxy layer; covers upper surface - protects leaf against loss 2. veins: transports water, nutrients and food - made of xylem and phloem 3. Mesophyll: contains cells that perform photosynthesis b/c they contain chloroplasts. 4. Guard cells Cells that open and close the stoma. Help to regulate the rate of transpiration by opening and closing the stomata. 5. Stomata: openings in leaf’s surface when open: - Gas exchange Allows CO2 in and O2 out of leaf - Transpiration - Allows excess H20 out of leaf

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What process involves using CO2 and H20 releasing O2 as a waste product? Photosynthesis What is a plant using this process to make Carbohydrates-glucose -

If the plant needs water for photosynthesis, why is water coming out of stoma.

Function of guard cells -

These stomata (leaf openings) naturally allow water to evaporate out.

Why would the plant close stomata with guard cells? -

Prevent excess water loss through transpiration (conserve water).

So what is the point of having stomata? Allow gas exchange for photosynthesis.

Transpiration Transpiration : loss of excess water from plant leaves 2. significance Transpiration causes enough pressure to help pull water and required nutrients up stem from roots. b. as apart of the water cycle trees transpire water hack into the atmosphere  Water molecules are quite strongly attracted to each other and tend to cling tightly together. This force is called “cohesion” Understanding photosynthesis – higher tier A two stage-stage process Photosynthesis is a process with two main stages 1. Light energy is used to split water, releasing oxygen gas and hydrogen ions 2. Carbon dioxide gas combines with the hydrogen to make glucose 6CO2 + 6H20 –(light energy)-----> C6H1206 + 602 Evidence for the two stages Experiments using isotopes of carbon, hydrogen and oxygen gave increased our understanding of photosynthesis. One of those experiments involves an isotope of oxygen, 18o. The more common isotope of oxygen in water or carbon dioxide, 16O can be replaced by 18O. The transfer of these 18O atoms into other substances cam be traced. The results were: -

Plants watered with water containing 18O atoms release oxygen gas containing 18O atoms. Plants supplied with carbon dioxide containing 18O atoms do not release oxygen gas containing 18O atoms

This shows that the oxygen gas produced by photosynthesis comes from water and not carbon dioxide. Movement of water up xylem vessels  When water enters the roots, hydrogen bonds link each water molecule to the next so the molecules of water are pulled up the thin xylem vessels like beads on a string. ( cohesion) The water moves up the plant, enters the leaves, moves into air spaces in the leaf, and then evaporates (transpires) through the stomata Hydrogen Bonding  a hydrogen bond is a weak interaction between a hydrogen atom of one molecule and, in this case, the oxygen of another molecule.  Water is a polar molecule, with the region around the oxygen atom having a slight negative charge and the regions around the hydrogen atoms having a slight positive charge.  In water, the negative regions on one molecule are attracted to the positive regions on another, and the molecules form hydrogen bonds. The process of transpiration  There are hundreds of stomata in the epidermis of a leaf. Most are located in the lower epidermis. This reduces water loss because the lower surface receives less solar radiation than the upper surface. Each

stoma allows the carbon dioxide necessary for photosynthesis to enter, while water evaporates through each one in transpiration.

Digestion in a mammal Animals are heterotrophs. They must eat energy rich food made by other organisms, either plants and other animals. In this section we will considered only the case of mammals, not all animals. The food a mammal eats is composed largely of complex carbohydrates, proteins,, and fats which must be digested before being absorbed into the body and used by the cells. Digestion mainly involves chemically breaking large molecules down into smaller

Physical Digestion - is the physical cutting & mashing of the food, mainly achieved by the chewing of food in the mouth. Breaking the food into smaller fragments increases the surface area available for chemical attack by enzymes. Chemical Digestion- involves digestive enzymes as suggested by the diagrams above. More details below. Digestive Enzymes: Agents of Chemical Digestion You will soon see a pattern here... a name ending in “-ase” is generally the name of an enzyme. Lipase Lipase enzymes attack lipids... the fats & oils, breaking them into individual “fatty acids” & glycerol. Glycerol is a small sugar-like molecule which holds 3 fatty acids together to make a fat molecule. For a lipase enzyme to digest a fat molecule, the fat must first be emulsified into water solution. This is achieved by secretions from the gall bladder. Amylase Many foods contain “starch”, a polymer of sugar molecules. There are several different types of starch, but the commonest is known as “amylose”. So (you guessed it!) the digestive enzyme that attacks it is called “amylase”. Nuclease is the general name for enzymes which digest nucleic acids, DNA & RNA. Human digestive system – structure and function

Which Organs Produce Which Enzymes?

Salivary Glands: amylase Stomach: a powerful protease commonly called “pepsin”. Pancreas: several proteases & peptidases, amylase, lipase, nuclease. Small Intestine: peptidases, maltase, sucrase, lactase. These enzymes finish off chemical digestion, ready for absorption. Absorption of digested nutrients    

The villi greatly increase the surface area of the intestinal lining available for absorption of the digested nutrients The surface layer is only one cell thick, so digested nutrients can be easily absorbed and carried to the blood capillary network inside. Water soluble nutrients such as amino acids & sugars are carried into the blood stream. Fatty acids & chemicals such as cholesterol are carried to a “lacteal” tube which drains into the Lymphatic System.

Water absorption in the large intestine  

By the end of the small intestine, most of the useful digested nutrients have been absorbed. through the large intestine, most of this water is re-absorbed from the gut by osmosis.

Gas Exchange in Animals Animals need oxygen for cellular respiration and need to get rid of the toxic product, CO2. The purpose of gas exchange is therefore to absorb )2 and remove CO2.

Circulatory system For most animals, internal transport is carried out by the Circulatory System... the blood, heart and blood vessels; veins, arteries and capillaries oxygen is carried in the red blood cells by haemoglobin Carbon dioxide Is partly carried by the hameoglobin in red blood ceels, but most of it is carried in the blood plasma, in the form of bicarbonate ions. Water Is carried as the liquid of blood plasma Salts, sugars, and amino aicds These are nutrients absorbed from the digestive system. They are generally water soluble and are carried sisolved in the blood plasma.

Lipids fats Absorbed from the digestive system are ‘packaged’ in a protein coat which makes the fat molecules dissolvable in water. Means that while not fully dissolved the molecules can be dispersed in water and carried without joining together into droplets of fat and separating the water. Red blood cells 

Contain the red pigment hemoglobin which carrier oxygen.

White blood cells 

Come in a huge variety of type , but all are involved with defense against diseases.

Blood vessels Arteries  

Carry blood from the heart out to the body tissues. The walls of an artery are thick and muscular to withstand the high pressure in the blood when the heart pumps.

Veins  

Carry deoxygenated blood back to the heart by the muscles. Low pressure and the walls of veins are thin.

Capillaries   

Tiny blood vessels which form a network throughout the body so every cell is close to a blood supply. The walls are only one cell think so diffusion of substances between blood and cells are efficient. Nutrients are exchanged from materials to capillaries

Structure and function of the heart

1. Deoxygenated blood from the body collects in the right atrium, which contracts, filling up the right ventricle. 2. The right ventricle contracts and pushes blood to the lungs. 3. In the lungs, blood loses carbon dioxide and picks up oxygen. 4. oxygenated blood returns to the left atrium, which contracts, filling up the left ventricle.

5. A contraction of the left ventricle expels oxygenated blood into the aorta, from which distributes blood throughout the body. 6. In the muscles and body organs, blood releases oxygen and nutrients, and absorbs food and water from the intestines. 7. Deoxygenated blood returns to the heart through the veins. Another cycle begins....