Waec 2024 Biology Obj & Essay Question And Answer Now Available

BIOLOGY OBJ
1-10: CCBBBBABAC
11-20: CCABDBAADD
21-30: BDADDABABA
31-40: ACCAACACCD
41-50: BBCAADCBBB

WAEC 2024 BIOLOGY COMPLETE ESSAY ANSWER…

(3ai)
(i) Discoloration: The meat may turn brown or green.
(ii) Mold growth: Visible mold or fungal growth may appear on the surface.
(iii) Odor: A foul smell or strong odor may develop due to bacterial growth.
(iv) Texture: The meat may become slimy or sticky.

(3aii)
Decomposition (or putrefaction) caused by microbial activity.

(3aiii)
TABULATE PLEASE

=FOUR METHODS OF PRESERVING THE MEAT=
(i) Refrigeration/Freezing
(ii) Salting
(iii) Smoking
(iv) Drying/dehydration

=ONE PRINCIPLE INVOLVED IN THE PRESERVATION METHOD=
(i) Low temperature slows down microbial growth
(ii) Salt dehydrates microbes and inhibits their growth
(iii) Smoke contains compounds that kill or inhibit microbes
(iv) Removal of water inhibits microbial growth

(3aiv)
(i) Temperature: High temperatures can accelerate the growth of bacteria and fungi, leading to faster decomposition of the meat.
(ii) Humidity: High humidity levels can create a conducive environment for microbial growth, increasing the rate of spoilage.

(3b)
(i) Dried maize grains: Airtight storage (to prevent moisture absorption and pest infestation)
(ii) Fresh tomatoes: Canning (to prevent spoilage and extend shelf life)
(iii) Vegetables: Freezing (to retain nutrients and prevent spoilage)
(iv) Beans: Drying (to reduce moisture content and prevent microbial growth)
(v) Milk: Pasteurization (to kill harmful bacteria and extend shelf life)

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(2a)
(i) Mouth;
The mouth is responsible for the initial mechanical breakdown of food through chewing and the enzymatic breakdown of starches through the action of saliva.

(ii) Skin;
The skin regulates body temperature through the process of sweating, which also helps to excrete excess salts and maintain homeostasis.

(iii) Tongue;
The tongue assists in the manipulation of food for chewing and swallowing, and contains taste buds that help in the sensory evaluation of food.

(iv) Kidney;
The kidneys filter blood to remove waste products and excess substances, producing urine, which helps to maintain the body’s fluid and electrolyte balance.

(v) Stomach;
The stomach produces gastric juices, including hydrochloric acid and digestive enzymes, which help in the breakdown of food into a semi-liquid form called chyme.

(vi) Small Intestine;
The small intestine is the primary site for nutrient absorption; it continues the process of digestion with the help of enzymes and bile, and absorbs nutrients into the bloodstream.

(vii) Large Intestine;
The large intestine absorbs water and salts from the material that has not been digested as food, and compacts the remaining material into feces for excretion.

(viii) Liver;
The liver produces bile, which aids in the digestion and absorption of fats, and processes nutrients absorbed from the small intestine, detoxifying harmful substances and storing nutrients.

(2b)
(i) Mouth (salivary glands produce amylase)
(ii) Stomach (produces pepsin)
(iii) Small intestine (produces various enzymes such as maltase, lactase, and sucrase; receives enzymes from the pancreas)

(2c)
(i) Amylase (in saliva) – Breaks down starches into sugars.
(ii) Pepsin (in stomach) – Breaks down proteins into peptides.
(iii) Lipase (from pancreas) – Breaks down fats into fatty acids and glycerol.

(2d)
(i) Glucose (from the breakdown of carbohydrates)
(ii) Amino acids (from the breakdown of proteins)

(2ei)
Excess salt can lead to increased blood pressure due to the retention of water, which increases the volume of blood.

(2eii)
(i) Energy – Carbohydrates in cassava provide a source of energy.
(ii) Protein – Groundnut soup contains proteins necessary for body repair and growth.
(iii) Nutrients – The meal provides essential vitamins and minerals required for overall health.

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BIOLOGY ANSWERS

(1ai)
Glomerulus:
(PICK ANY ONE)
(i) It filters blood to form glomerular filtrate.
(ii) It removes waste products and excess substances from the bloodstream.
(iii) It initiates the urine formation process by allowing water and small molecules to pass through while retaining larger molecules like proteins.

(1aii)
Bowman’s capsule:
(PICK ANY ONE)
(i) It collects the filtrate produced by the glomerulus.
(ii) It forms primary urine by capturing the filtrate and directing it into the nephron.
(iii) It serves as a funnel, guiding the filtrate into the proximal convoluted tubule for further processing.

(1aiii)
Proximal convoluted tubule:
(PICK ANY ONE)
(i) It reabsorbs water, ions, and nutrients from the filtrate back into the bloodstream.
(ii) It plays a crucial role in secreting waste products such as hydrogen ions and ammonia into the tubular fluid.
(iii) It maintains pH balance by selectively reabsorbing bicarbonate ions and secreting hydrogen ions.

(1aiv)
Distal convoluted tubule:
(PICK ANY ONE)
(i) It reabsorbs sodium and water, thus playing a key role in regulating blood pressure and fluid balance.
(ii) It secretes potassium and hydrogen ions, which helps in maintaining electrolyte and acid-base balance.
(iii) It also regulates calcium and phosphate levels in the blood, contributing to bone health and metabolic functions.

(1b)
|ORGANISM | Structure.. |..Form in which|

|Paramecium|Contractile vacuole|Liquid (water)

|Flatworm |Flame cells| Ammonia|

|Earthworm|Nephridia | Urea|

|Cockroach|Malpighian tubules|Uric acid|

|Human | Kidneys| Liquid(urine)|

|Plant | Stomatal pore| Gaseous (water vapor, oxygen, carbon dioxide

(1c)
(PICK ANY FIVE)
(i) Oxygen
(ii) Carbon dioxide
(iii) Water vapor
(iv) Resins
(v) gums
(vi) Latex
(vii) Tannins
(viii) Essential oils

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(5ai)
Competition refers to the struggle between organisms for limited resources such as food, water, mates, or territory.

(5aii)
(I) Intraspecific competition: Competition occurring between members of the same species.
(II) Interspecific competition: Competition occurring between individuals of different species.

(5aiii)
(PICK FOUR)
(I) Food
(II) Water
(III) Shelter
(IV) Territory
(V) Mates
(VI) Light (for photosynthesis in plants)

(5aiv) Competition influences succession by shaping the composition and abundance of species in an ecosystem. Intense competition among species in the early stages of succession can lead to the dominance of certain species, while others may be excluded. As succession progresses and environmental conditions change, the intensity and outcomes of competition may also change, affecting the trajectory of succession.

(5bi) Structural adaptation refers to physical features or characteristics that enhance an organism’s survival in its environment.

(5bii)
(PICK FOUR)
(i) Camouflage
(ii) Mimicry
(iii) Protective coloration
(iv) Structural modifications (e.g., wings, claws, teeth)
(v) Body shape (e.g., streamlined bodies for aquatic animals)
(vi) Specialized appendages (e.g., long necks in giraffes)

(5c)
(PICK FOUR)
(i) DNA fingerprints
(ii) Facial features
(iii) Hair characteristics
(iv) Blood type
(v) Skin color
(vi) Iris patterns

(5e) An example of a plant found in the tropical rainforest is the orchid.