Biology Revision Midterm 2024-25 (PEES)

BIOLOGY REVISION MIDTERM Grade 9 PEES 2024-25 IMPORTANT DEFINITIONS Movement: an action by an organism or part of an organism causing a change of position or place. Respiration: the chemical reactions that break down nutrient molecules in...

BIOLOGY REVISION MIDTERM Grade 9 PEES 2024-25 IMPORTANT DEFINITIONS Movement: an action by an organism or part of an organism causing a change of position or place. Respiration: the chemical reactions that break down nutrient molecules in living cells to release energy for metabolism. Sensitivity: the ability to detect or sense stimuli (changes) in the internal or external environment and to make appropriate responses. Growth: a permanent increase in size and dry mass by an increase in cell number or cell size or both. Reproduction: the processes that make more of the same kind of organisms. Excretion: the removal of toxic materials, the waste products of metabolism and substances in excess of requirements. Nutrition: the taking in of materials for energy, growth and development. A species is defined as a group of organisms that can reproduce to produce fertile offspring. A tissue is a group of similar cells that work together to carry out a particular function An organ is a group of different types of tissues that work together to perform a specific function DIFFUSION The net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient as a result of random movement. OSMOSIS The net movement of water molecules from a region of its higher water potential (dilute solution)to a region of its lower water potential (concentrated solution ) through a partially permeable or semi permeable membrane ACTIVE TRANSPORT Movement of particles through a cell membrane from a region of its lower concentration to a region of its higher concentration against the concentration gradient using energy from respiration by the usage of carrier proteins. Enzymes proteins which act as biological catalyst to speed up the metabolic reactions in living body without being changed or used up in the reaction. Catalyst Any substances that speed up a chemical reaction without getting changed by the reaction is called catalyst. COMPARISONS of VERTEBRATES (all vertebrates have backbone) Body covering Reproduce by breath through Extra Mammals Fur /hair Give birth to lungs external ear Youngs (pinnae) mammary glands placenta Birds feathers Lay hard shell lungs Beak ,wings eggs on land Reptiles Dry scales Lay soft shell lungs (leathery ) eggs on land Amphibians No body Lay eggs Adult breathe Show covering, without shell through lungs metamorphosis smooth moist in water tadpole(larvae) skin breathe through gills Fish Wet scales Lay eggs Gills Fins without shell in water * mammals and birds are warm blooded(endothermic) but reptiles amphibians and fish are cold blooded(ectothermic) animals COMPARISONS of ARTHROPODS (All arthropods have exoskeleton, jointed legs , body divided into segments) GROUPS No. of jointed legs No. of antennae Body segments Insects 3 pairs 1 pair 3 (head, thorax abdomen ) Arachnids 4 pairs x 2 (cephalothorax and abdomen) Crustaceans More than 4 pairs 2 pairs 2/3 Myriapods Many pairs 1 pair Many similar segments (*insects : wings ) Comparisons of Monocot and Dicot Monocot Dicot Number of floral parts 3 or Multiples of 4/5 or multiples of Veins parallel Reticulated/ branched Number of cotyledons 1 2 Comparisons of Plant , Animal and bacterial cell Plant cell Animal cell Bacterial cell Cell wall Pr. (cellulose) Ab. Pr. (not cellulose) Cell membrane Pr. Pr. Pr. cytoplasm Pr. Pr. Pr. ribosomes Pr. Pr. Pr. Chloroplast Pr. Ab. Ab. Mitochondria Pr. Pr. Ab. Nucleus Pr. Pr. Ab. Large permanent Pr. Ab. Ab. vacuole Plasmids Ab. Ab. Pr. Comparison of biological molecules carbohydrates Proteins lipids Elements Carbon hydrogen Carbon, hydrogen Carbon and oxygen oxygen and hydrogen and nitrogen oxygen  Benedict’s Iodine Biuret test Ethanol DCPIP Test Test Emulsion Test Test for reducing starch protein lipids/fats Vitamin sugars C Positive Brick red Blue black Purple Cloudy colorless result /lilac /milky Negative Blue Orange blue Transparent blue result brown *only Benedict Test requires heat * Based on the amount of reducing sugar / glucose, Benedict ‘s Test shows the colour change from clear blue to green, yellow, orange and red. Large molecule Small molecule Cellulose (makes the plant cell wall ) Glucose Glycogen ( stored form of carbs in animal liver) Glucose Starch ( stored form of carbs in plants) Glucose Proteins Amino acids Lipids 3 Fatty acids and 1 glycerol Large molecule Enzyme Small molecule Protein protease Amino acids Starch amylase Maltose /glucose Fats and oils /lipids lipase Fatty acids and glycerol COMPARISON OF DIFFUSION OSMOSIS AND ACTIVE TRANSPORT Diffusion Osmosis Active transport energy required no no yes concentration down down Up/against gradient from high to low yes yes no from low to high no no yes Always involve no yes yes movement across the partially permeable membrane Involves movement of yes no no both gases and solute Factors affecting diffusion : (for faster diffusion) factor Increase/decrease Temperature increase Concentration gradient increase Diffusion distance decrease Surface area increase How the plant and animal cell behave in different solutions Plant cell Animal cell Dilute solution (high Water moves in the cell Water moves in the cell water potential outside) from H.W.P. to L.W.P across from H.W.P. to L.W.P the P.P.M the vacuole across the P.P.M so it can becomes bigger , the cell swells up it can becomes turgid and exert eventually burst as there turgor pressure is no cell wall to resist the pressure Concentrated solution water moves out of the animal cells shrink / (low water potential cell due to low water shrivel / crenated due to outside) potential of water in the movement of water solution. so that the cell occur from cell (H.W.P.) loses turgidity and becomes to concen. Solution flaccid/plasmolysed (L.W.P) And the plant may start wilting(lack of turgor pressure) isotonic solution (same water moves in and out of the size of the cell water potential ) the cell so there is no overall remains same there is no change in the cell size/mass net movement of water in and out of cell How Enzymes work FACTORS/CONDITIONS AFFECTING ENZYME ACTIVITY The enzymes work best at their optimum temperature and the optimum Ph Heating to high temperatures (beyond the optimum) will break the bonds that hold the enzyme together and it will lose its shape -this is known as denaturation Substrates cannot fit into denatured enzymes as the shape of their active site has been lost MAGNIFICATION DNA (two strands coiled together to form double helix) Four types of nitrogenous bases where A=T G=C % A =%T %G =%C