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Sunday, 9 December 2018

December 09, 2018

The Main Structural Adaptations of a Leaf to Photosynthesis





Structure - Adaptation

• Leaf Stalk - Able to hold leaf blade in the best position to receive maximum amount of sunlight

• Leaf Blade - Large surface r area for receiving sunlight; thin structure to ensure that the carbon dioxide that enters the leaf can rapidly reach each leaf cell by diffusion

• Stomata - Present on leaf surface e in large numbers to allow entry and exit of gases and water vapour from leaf

• Intercellular Spaces - present through out the leaf, linking the interior of leaf to the external environment,  enabling diffusion and distribution of gases and water vapour from and to all photosynthesis cells

• Transport Tissue - Well distributed throughout leaf to bring water to each photosynthesis cell and remove manufactured food from it

• Mesophyll tissue - Cells , especially at the upper surface, contain numerous chloroplasts to carry out photosynthesis

December 09, 2018

Mineral Nutrition in Plants





Element - Function - Deficiency Symptoms - Sources

                        MAJOR ELEMENTS

• Sulphur (s) - Formation of certain proteins in the protoplasm - Yellowish of leaves ; stems become slender - Sulphates in the soil

• Phosphorus (p) - Formation of coenzymes and nucleoproteins ; acting as buffer ; nuclear division - Poor , weedy growth; stems and leaves become purplish ; mottling of lower leaves - Phosphate in  the soil

• Nitrogen (n) - Synthesis of amino acids, proteins , nitrogenous bases and chlorophyll - Extremely stunted growth with very small yellow leaves - Nitrates in the soil; ammonium salts in the soil

• Calcium (c) - Healthy growth ; cell wall formation; neutralizing acids; activating enzymes - Weak, stunted growth; poor root development - Calcium salts in the soil

• Iron (fe) - Formation of chlorophyll - Poor growth ; yellowing of leaves - Iron salts in the soil

• Magnesium (mg) - Formation of chlorophyll - Poor growth; yellowing of leaves - Magnesium salts in the soil

• Potassium (k) - Cell formation; regulation of certain cell activities - Very poor growth ; leaves turn orange or brown - Potassium salts in the soil.

Minor elements : minor elements are mainly required for the activity of enzymes.
December 09, 2018

Minerals Required By Humans




Mineral - Function - Deficiency symptoms - Source / Daily needs

• Sodium - An important component (about 1%) of blood plasma; maintains the correct osmotic pressure of the body fluid; needed in the transmission of impulses in nerves, sensory cells and muscles, and for normal cell membrane permeability - Dehydration, muscle cramps , kidney failure ( Excess causes oedema and hypertension) - Salt, Natural foods especially meat, milk and eggs ( 5 - 8 g)

• Chlorine - Maintains correct osmotic pressure of body fluids - Muscle cramps (excess causes oedema) - Salt , natural food (3 g)

• Potassium - Similar Functions as Sodium - Leads to muscle paralysis - All natural foods (2 mg)

• Calcium - A Major component of bones and teeth; needed for clothing of blood, proper functioning of the heart and nervous system, and normal contraction of muscles - Softening of bones, rickets in children - Milk, cheese, eggs, fruit, green vegetables, almonds (1 g)

• Phosphorus - Involved in the transfer of energy and hence, requires for most chemical reactions in the body ; essential component of DNA and RNA, a major component of bones and teeth - Rickets - Fish, shellfish , eggs, milk, cheeses (1.5 g) 

• Magnesium - A major component of bones ; activities glycolytic enzymes in muscles in muscle - Weakness , depression and disturbance in muscle contraction - Leafy vegetables. Nuts, sea foods (350 mg)

• Iron - Structural and functional component of haemoglobin in red blood cells, myoglobin in  muscle cells and enzymes (cytochromes ) involved in cell respiration - Anaemia - Liver, meat, eggs, green vegetables (10 mg)

• Copper - Fair haemoglobin formation - (-----) - Meat liver (1 mg)

• Manganese - For formation of haemoglobin and enzyme action - (-----) - (---) (3 mg)

• Iodine - Needed for the synthesis of the thyroid hormone and for normal reproduction in mammals - Goitre, poor growth - Sea foods (0.1 mg)

• Fluorine - Hardens bones and teeth - Dental caries - Milk (trace)

• Cobalt - for haemoglobin formation - Pernicious anaemia - Meats
December 09, 2018

Vitamins Required by Humans





Vitamins - Function - Deficiency Symptoms - Sources / Daily needs

             FAT SOLUBLE VITAMINS

• A -  Needed for proper functioning of epithelial tissue such as skin, mucous membranes ; component of visual pigments, needed for vision in dim light; essential for normal growth - Skin becomes flaky (horny and dry ) ; night blindness and xerophthalmia (can lead to permanent blindness) - Fish liver oil, palm oil, milk, milk, egg yolk; green and yellow vegetables , fruits (1.5 mg)

• D ( calciferol) - Increases absorption of calcium and phosphorus in the intestines ; calcification and hardening of bones - Rickets in children (poor bone and teeth formation) ; softening of bones in adults - Fish liver oils, egg yolk, butter (synthesized in skin when exposed to sun ultraviolet rays) (0.01 mg)

• E (tocopherol) - Protects fatty acids and cell membranes from oxidation - (--) - Leafy vegetables, seeds , eggs, milk, margarine (15 mg) 

• K - Synthesis of blood clotting factors - Slow clotting of blood leading to severe bleeding from cuts - Liver, vegetables (made by intestinal bacteria) (0.03 mg)


         WATER SOLUBLE VITAMINS

B ( thiamine) - Needed for synthesis of coenzymes involved in cellular respiration - Beri - Beri , ( wasting of muscles, paralysis); stunted growth - Yeast , rice bran , beams, groundnuts, liver (1.0 mg)

• B2 (riboflavin) - Formation of coenzymes involved in cellular respiration - Cracking of skin around corners of nose, mouth and eyes - Eggs, liver, kidney, yeast, leafy vegetables (2 mg)

• B3 (niacin or nicotinic acid) - Formation of coenzymes involved in cellular respiration - Pellagra (scaly pigmented skin, sore mouth and tongue, nervous disorder) - Yeast , liver, milk, eggs, whole grains (made by intestinal bacteria) (18 mg)

• B5 (pantothenic acids) - Formation of coenzymes involved in cellular respiration - Disorder of nervous system and gut - Yeast, eggs, rice bran, (10 mg)

• B6 (pyridoxine) - Formation of enzymes involved in synthesis of amino acids - Anaemia, diarrhoea - Yeast , eggs, cereals (2 mg)

• B12 (cyanocobalamin) - Formation of red blood cells - Pernicious Anaemia - Kidney, liver, fish, milk (3 mg) 

• Folic acids - Formation of red blood cells - Anaemia - Leafy vegetables, liver (0.5 mg)

• C (ascoribic acid) - Requires for healthy connective tissues, bones and dentine; may help to resist infection - Scurvy ( swelling of joints and gums, loosening of teeth, hemorrhages of the skin and membranes) - Fresh citrus fruits, pawpaw, guava, fresh leafy green vegetables (easily destroyed by heat)

December 09, 2018

Characteristic Features of the Vertebrate Groups




Class - Cold/Warm blooded - Skin - Limbs - Gaseous exchange - Reproduction/ parental care

• Fishes e.g tilapia - Cold blooded - Covered with scales and slime - Limbs modified into fins - Through gills - Fertilization is external; eggs are laid in water; young look like adults; parental care rare

• Amphibians e.g toads, frogs - Cold blooded - Soft and moist - Two forelegs and two hind legs - Through gills in young; skin and lungs in adults - Fertilization is external; eggs are laid in water; complicated life cycle where young look different from adults; no parental care

• Reptiles e.g. lizards - Cold blooded - Coveted with dry scales - Two forelegs and two hind legs with toes ending in claws - Through lungs - Fertilization is internal; eggs with shells are laid on land and hatch into young which look like adults; no parental care

• Birds e.g. pigeons, hens - Warm blooded - Covered with feathers (scales on feet) - Forelimbs modified into wings; hind legs with toes ending in claws - Through lungs - Fertilization is internal; eggs with shells are laid on land and hatch into young which look like adults; parental care present in most

• Mammals e.g rabbits, goats, lions, humans - Warm blooded - Covered with hair (fur) - Two forelegs and two hind legs ending in claws - Through lungs - Fertilization is internal; young develop in mother body and are born alive; parental care with young feeding on milk secreted by the mother's mammary glands.
December 09, 2018

Characteristics Features of the Main Invertebrate Groups





Phylum - Cellular organisation - Coelom - Body symmetry - Reproduction - Distinguishing Features


• Porifera or Sponges - No tissues - None - Asymmetrical - Sexual and asexual; usually hermaphrodites - Aquatic , adults non motile; filter feeders; possess pore and collar cells

• Coelenterates e.g. jellyfish, hydra, corals - Tissues - None - Radial - Budding and sexual; individuals are hermaprodites - Polyp and Medusa forms; stinging cells on tentacles

• Platyhelminthes e.g flukes, tapeworms - Organs - None - Bilateral - Sexual ; individuals are hermaprodites - Flag body with definite head and tail end

• Nematodes e.g. Ascaris , hookworm - Organs - pseudcoelom - Bilateral - Sexual; separate male and female individuals - Cylindrical unsegmented body

• Annelids e.g. earthworms, leeches - Organ systems - Coelom - Bilateral - Sexual; male , female or hermaproditic individuals - Cylindrical segmented body

• Molluscs e.g. snails, clams, oysters - Organ system - Coelom - Bilateral - Sexual; separate male and female individuals - Unsegmented body, muscular foot, mantle cavity; shells present in most

• Arthropods e.g. crustaceans, insects,  spiders, millipedes - Organ system - Coelom - Bilateral - Sexual ; separate male and female individuals - Jointed appendages ; chitinous exoskeleton; specialized segments and sensory system

• Echinoderms e.g. starfish, sea urchins, sea cucumbers - Organ system - Coelom - Radial (adult); bilateral (Larva) - Sexual ; separate male and female individuals - Spiny skeleton; system of water cans; tube feet
December 09, 2018

Levels of Biological Organization Showing Levels of Specialization in Various Representative Organisms




Level of organization  -  Representative organisms for level of Specialization


• Macro Molecule (non living) - Composed of atoms and molecules, able to carry out simple functions, e.g. enzymes, DNA, RNA

• Organelle (non living) - Composed of molecules and macromolecules, able to carry out complex functions  like photosynthesis, respiration e.g. chloroplasts , mitochondria

• Cell (living) - Composed of macromolecules and organelles; the basic unit of living organisms, capable of carrying out all living activities, e.g. blood cells, phloem cells

• Tissue - Composed of similar cells specialized to carry out particular functions, e.g. muscle tissue in animals (contractile), epidermis in plants (protective covering)

• Organ - Body part, composed of several types of tissues, capable of carrying out a specialized function, e.g. heart in animals (acting as a pump) , leaf in plants (making food by photosynthesis)

• Organ system -  Composed of functionally related organs, e.g. the circulatory system in animals consists of the heart, blood vessels and blood (for transporting materials throughout the animal) ; root system in plants

• Complex multicellular organism - Composed of several organ systems