Cell Diversity

 Cell Diversity

By Naomi Keddy

Tissue is a group of similar cells modified to carry out the same function

Types of plant tissues:

·         Dermal tissue: surrounds and protects the plant. Eg Epidermis

·         Vascular Tissue: transports minerals in the plants. Eg Xylem; transports water and dissolved minerals and Phloem transports food.

Four Types of animal tissues:

·         Connective tissue: consists of cells dispersed in a matrix and surrounds its and supports the body.

Types of connective tissue

-Dense Connective tissue

-Adipose tissue

-Areolar tissue

-Compact bone

-Blood

Examples of connective tissue:

1.       Cartilage: Provides strength and flexibility

2.       Bone: Allows movement, Stores calcium and contains forming blood cells

3.       Blood: Transports oxygen and carbon dioxide.

Tissue Culture: is the growth of cells in sterile nutrient medium outside the body.

In vitro means outside of the body

Micropropagation: is the growth of large numbers of cells of a parent plant.

Monoclonal antibodies: combine with a specific type of antigen, this may be used to attach to and show the presence of antigens on cancer cells.

Growth of Skin: Patients skin grown outside of the body and new skin is grafted onto the wound, this is called a skin graft and is often used on badly burnt patients due the fact the their skin tissue too bad damaged to repair itself.

Conditions necessary for Tissue growth

• Oxygen

• Nutrients

• Growth factors and hormones

• Correct pH

• Optimum temperature

• Sterile conditions

• Freedom from competition

An Organ: is made up of a number of tissues working together to carry out the same function.

An Organ System: contains a number of working organs working together to carry one or more functions.          

Excretion

Excretion

By Naomi Keddy

Homeostasis: is the maintenance of a constant external environment in an organism. Excretion helps homeostasis Example of excretion helping homeostasis is temperature regulation in animals. The control of temperature in the body is needed because temperature regulates the chemical reactions.

Ectotherms: gain or lose heat to their external environment.

Endotherms: generate their own heat from metabolic reactions.

Function of the skin:

Protection:

• Epidermis protects against damage.

• Melanin protects against ultraviolet radiations.

• Sebum helps keep the epidermis intact.

• Vitamin D is made in the skin

• Fats are store in the skin for heat and energy.

• Skin is used as sense organ for touch, pain or temperature

• Excretion sweat removes water and salt from the body.

Temperature regulation:

• Cold conditions cause:

1. Hairs to stand up to keep the skin warm.

2. Blood vessels become narrow to retain heat.

3. Shivering is movement to keep the body warm.

• Warm conditions cause:

1. Sweating, which cools the body due evaporating.

2. Blood vessels widen to lose heat.

 The role of the excretory system:

• Regulating body temperature.

• Controlling osmosis

• Controlling the concentration of body fluids

• Removing waste products.

Organs of Excretion:

• Lungs: excrete water and carbon dioxide.

• Skin: excrete water and salt.

• Kidneys: excrete water, salt and urea in the form of urine.

The Human excretory system:

The Kidneys:

The urinary system consists of two kidneys, two ureters, the bladder and the urethra.

The Kidneys are located just below the diaphragm.

The mains processes of the kidneys:

• Filtration: The incoming of the blood into the kidneys is filtered. This takes place in the outer cortex.

• Reabsorption: Some useful materials are taken back into the blood and this is called reabsorption. It occurs in the cortex and the medulla.

• Secretion: Some substances are secreted from the blood into the cortex such as potassium and hydrogen ions. 

The Functions of the kidneys:

1. Excretion: The kidneys remove waste products from the bloodstream and convert them to urine.
2. Water content: The kidneys control the water content by varying the water content of urine.
3. Salt concentration: The kidneys control the salt concentration of body fluids by varying the amount of salt released in the urine.
4. pH Control: The kidneys control the pH of the body fluids by producing urine that is either more or less acidic. 

The Nephron:

 The nephron carries out the function of the kidneys and it is located in the cortex and the medulla of the kidneys.

The processes of the nephron:

• Filtration means that water and small molecules pass from the blood to the nephron.

1. Blood entering the nephron in the afferent arteriole contains waster products.

2. Filtration takes place in the glomerulus. Small molecules such as glucose, amino acids, vitamins and minerals are forced out of the plasma into bowman’s capsule. 

• Reabsorption means that molecules pass from the nephron back into the blood. 

1. Most of the water is reabsorded by osmosis. Useful molecules such as glucose, amino acids and vitamins are reabsorbed by diffusion and active transport ( means it requires energy in the form of ATP)

2. The descending limb of the loop of Henle is permeable to water so small amount of water is reabsorbed by osmosis.

3. The ascending limp of the loop of Henle is permeable to salts. 

The hormone ADH:

• Is released from the pituitary gland.

• Controls the volume of urine formed.

• Is released when plasma has too little water or too much salt.

ADH Causes:

• Increased reabsorption of water in the distal tubule and the collecting ducts.

• A low volume of urine.

• ADH is not released when we drink sufficient water or consume a low salt diet.

Human Nutrition: Macronutrients

Human Nutrition 

By Naomi Keddy

Why Do Organisms need Food?

Well Organisms need food to maintain metabolism and the continuity of life for all living things. We need to maintain metabolism to maintain homeostasis. We need nutrients to carry out metabolic reactions, as a source of energy and for growth and repair. Nutrition is the study of food, its composition, structure, properties. amounts required and its effects on the body.

What are Macronutrients? 

Macronutrients are the nutrients that are required in large amount in the body and they are Protein, Carbohydrates and Lipids.

What is protein? 

Fig.1 Complex structure of protein

Protein is composed of the elements Carbon, Hydrogen, Oxygen and Nitrogen. Protein is the only nutrient that contains Nitrogen, which is essential for growth in the body. Sometimes protein contains smaller amounts of sulfur, phosphorus and other elements. The basic structure of protein is a build up with amino acids. Peptide bonds are formed when amino acids join together. In this reaction a H2o molecule is lost. The reserve of this reaction is called hydrolysis and it involves the addition of water and enzyme action and this occurs in digestion. There are two sources of protein. Protein that comes from animals and protein that comes from plants. Examples of plant source protein are soya beans, peas and beans. Examples of animal source protein are Chicken, milk, eggs and meat. Structural role of protein is to form structures such as hair, nails and muscles. 

Denaturation  is the unfolding of the protein chain resulting in an irreversible change in shape and the lost of its function. 

Deamination is using protein as a source of energy to control reactions. Excess protein that is not required for growth and repair is deaminated in the liver. An Excess amount of Nitrogen in the body can be toxic the body so that is why excess amount of protein has to be deaminated in the liver. Metabolic role of protein in the body is is used by enzymes to control reactions. 

Fig.2 Biuret test

The laboratory test for protein is the biuret test. If Protein is present it would change to a purple colour and if absent it would result in a blue colour.

What are Carbohydrates?

Fig.3 Structure of Carbohydrate

Carbohydrates are composed of the elements Carbon, Hydrogen and Oxygen. Carbohydrates are mainly found in plant foods. Plants makes their own food from a process call photosynthesis resulting in the production of glucose which is a carbohydrate. Carbohydrates are really good in the diet because they are a slow releasing energy. Carbohydrates are made up of sugar units. There are three types of carbohydrates which are broken into how many sugar units. 

Monosaccharide is one sugar unit. e.g Glucose and fructose. 

Disaccharide is two sugar units. e.g sucrose and maltose. 

Polysaccharide is many sugar units. e.g Starch and glycogen. Carbohydrates carry out several functions such as heat and energy to the body; they are stored as fat to the body. Fibre is good in the diet, because it is a substance that is plentiful in the outside layers of fruit and vegetables and the husks of grains. It is not digested or absorbed by the body but moves quickly through the small intestine and it is excreted out as waste. This helps prevent bowel disease. Sources of carbohydrates are bread, potatoes, rice and flour. 

The laboratory test for carbohydrates is Benedict's test (For Reducing Sugar) and Iodine test (Test for Starch). 

Fig.4 Benedict's test

 The Benedict's test, if sugar is present it would result in a brick red colour and it is negative it would result in a blue colour. 

The iodine test, if starch is present it would change to a blue-black colour and if absent it would result in a red-yellow colour.

Fig.5 Iodine test

                 

                                                                

What are Lipids?

Lipids are fats and oils that are composed of the elements Carbon, Hydrogen and Oxygen. Fats are solid at room temperature and oils are liquid at room temperature. Fats are divided into two types: Saturated fats and unsaturated fats. Saturated fats are fats that come from an animal . Saturated fats are known as the bad kind of fats. Unsaturated fats are fats that come from plant sources. 

The structure of lipids is glycerol and three fatty acid which is called triglyceride. 

Fig.6 Triglyceride

Glycerol and two fatty acids and a phosphate  are called phospholipid. 

Fig.7 Phospholipid

The structural role of lipids is heat and energy and protection of organs. The overuse of lipids may lead to stokes, heart disease and obesity. The metabolic role of lipid is to be broken down in respiration to release energy. The laboratory test for lipids is using brown paper, if it is a lipid it would stain a wet look and it isn't it won't be visible.