2023 NECO Biology (OBJ & Essay) Answers [21st July]
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NECO JUNE/JULY 2023 FREE BIOLOGY OBJ & ESSAY (BIO) QUESTION AND ANSWER ROOM 
 
Friday, 21st July 2023
Biology (Objective & Essay)
10:00am - 12:30pm


A. 2023 NECO BIOLOGY (OBJECTIVES) ANSWERS:

1-10: BBEDACCAEE
11-20: DDCEADBAED
21-30: EBBBEADBDD
31-40: EDACCCBCEA
41-50: EBBCACBAEC
51-60: DDABEDDDBE

B. 2023 NECO BIOLOGY (ESSAY) ANSWERS:

TYPED VERSION

NOTE: Answer THREE questions only

(1ai)
The cell theory states that all living organisms are composed of one or more cells. The cell is the basic unit of structure and organization in living organisms. All cells arise from pre-existing cells through cell division.

(1aii)
(PICK ANY TWO)
(i) Matthias Schleiden
(ii) Theodor Schwann
(iii) Rudolf Virchow
(iv) Robert Hooke

(1bi)
(i) They have bright and colorful petals
(ii) They are full of nectar
(iii) They have strong fragrance
(iv) They are funnel-shaped flowers
(v) The flowers are large and if the flowers are small they are in groups.

(1bii)
-Ginger: Rhizome
-Banana: Rhizome
-Sweet potato: Tuber

(1c)
The digestion of bread begins in the mouth, where chewing breaks it down into smaller pieces. Saliva containing enzymes starts breaking down starch into sugars. The chewed food moves down the esophagus to the stomach, where gastric juices and acids further break down proteins. The partially digested mixture, called chyme, then enters the small intestine. Here, pancreatic enzymes and bile continue the breakdown of carbohydrates, proteins, and fats. The small intestine absorbs the nutrients, passing them into the bloodstream. The indigestible parts and water enter the large intestine, where water is absorbed, and waste forms into feces. Finally, the remaining waste is eliminated through the anus during defecation. This process ensures the body can absorb essential nutrients from bread and other food for energy and nourishment.
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(2a)
Amoeba --> Hydra --> Tilapia --> Toad --> Snake

(2aii)
(i) The fruit is small and lightweight, which allows it to be easily lifted and carried by the wind.
(ii) The fruit is equipped with pappus hairs, which are bristle-like structures that act as parachutes.
(iii) The fruit has a winged shape or flat structure that aids in catching the wind and facilitates its transportation over long distances.

(2b)
Aim: To show that shoots of plant is positively phototropic.

Apparatus:
Potted plant, Light source (lamp or sunlight), Ruler or measuring tape, Potting soil, Watering can, Marker or labeling tags, Water

Method/Procedure:
(i) Select a healthy potted plant with young shoots, preferably one that has not been exposed to light for some time (e.g., keep it in a dark room for a day before the experiment).
(ii) Place the plant on a flat surface in a well-lit room but ensure that the light source is coming from one specific direction.
(iii) Water the plant adequately to ensure it is not water-stressed during the experiment.
(iv) Measure the initial height of the shoot from the soil surface to the tip using a ruler.
(v) Mark the direction of the light source for reference.
(vi) Allow the plant to grow for 24 hour.
(vii) Measure the final height of the shoot after 24 hours.
(viii) Record any changes in the orientation of the shoot with respect to the light source.

Observation:
The plant shoot should exhibit growth bending or curving towards the direction of the light source. This bending indicates positive phototropism, as the plant is actively growing towards the light.

Conclusion:
The experiment demonstrates that plant shoots are positively phototropic, meaning they respond to light by growing towards the light source.

(2c)
PLEASE TABULATE:

Aerobic Respiration:
(i) Requires oxygen as the final electron acceptor in the electron transport chain.
(ii) Produces a large amount of ATP (36-38 ATP molecules per glucose molecule)

Anaerobic Respiration:
(i) Does not require oxygen; uses other electron acceptors or fermentation pathways
(ii) Produces a smaller amount of ATP (2 ATP molecules per glucose molecule in lactic acid fermentation, and 2 ATP molecules and 2 NADH molecules per glucose molecule in ethanol fermentation.
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(3ai)
(PICK ANY TWO)
(i) Ponds
(ii) Rivers
(iii) Lakes

(3aii)
PLEASE TABULATE

Complete Metamorphosis:
(i) It has four distinct stages which are egg, larva, pupa, and adult.
(ii) Larva looks completely different from the adult.

Incomplete Metamorphosis:
(i) It has three stages which are egg, nymph and adult.
(ii) Nymphs closely resemble adult forms

(3b)
Aim: To demonstrate that chlorophyll is necessary for photosynthesis to occur in a plant.

Apparatus:
Two healthy potted plants of the same species and size, a dark cupboard or room, a light source, stopwatch, water, watering can

Method/Procedure:
(i) Ensure both potted plants are well-watered and healthy before starting the experiment.
(ii) Label one plant as the "Control" and the other as the "Test."
(ii) Place the "Control" plant in the well-lit room.
(iii) Place the "Test" plant in a dark cupboard or room where it will not receive any light.
(iv) Leave both plants undisturbed for 24 hours.

Observation:
After the specified duration, observe the "Control" plant in the well-lit room. It should appear green and healthy.
Observe the "Test" plant that was kept in the dark. It may appear pale or yellowish, indicating a lack of chlorophyll.

Conclusion:
The experiment demonstrates that chlorophyll is necessary for photosynthesis to occur in plants.

(3ci)
(i) Overuse of Chemical Fertilizers
(ii) Deforestation and Land Clearing
(iii) Overgrazing
(iv) Monoculture Farming

(3cii)
(i) Prolonged exposure to high levels of noise can cause permanent hearing impairment and damage to the sensory cells in the inner ear, leading to hearing loss.
(ii) Continuous exposure to noise pollution can cause stress and anxiety in humans and animals.
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(4ai)
(i) Diversity of Crops: Rotate a variety of crops in the system to prevent the continuous cultivation of the same plant species. This helps reduce the build-up of pests and diseases specific to particular crops and improves overall soil health and fertility.

(ii) Balancing Nutrient Needs: Plan the sequence of crops in such a way that they have different nutrient requirements. For example, leguminous crops can fix nitrogen in the soil, benefiting the subsequent crop that requires higher nitrogen levels.

(iii) Pest and Disease Management: By avoiding the continuous cultivation of susceptible crops, the prevalence of pests and diseases is reduced, minimizing the need for chemical interventions.

(4aii)
(i) Reduced leaf surface Area to minimise water loss through transpiration.
(ii) Thick waxy cuticle which helps to reduce water loss by evaporation.
(iii) Possession of water-storing tissues that store water, allowing them to survive in arid environments.
(iv) The use of Crassulacean Acid Metabolism (CAM) photosynthesis that allows them to open their stomata at night to reduce water loss and fix carbon dioxide, which is then used for photosynthesis during the day.
(v) Presence of deep root systems that can tap into underground water sources, enabling them to access water during dry periods.

(4bi)
(i) Birds and reptiles exhibit similar forelimb bone structures, indicating a shared evolutionary history. Both have similar bone elements like the humerus, radius, and ulna, although they have different functions in flight and locomotion.
(i) The presence of scales in reptiles and feathers in birds suggests a common ancestry. Feathers are thought to have evolved from reptilian scales, with early feathers possibly providing insulation before developing into structures useful for flight.
(iii) Both birds and certain reptiles, such as crocodilians, exhibit nest-building behaviors. This shared trait indicates a common origin or convergent evolution in response to similar environmental challenges.

(4bii)
(i) It helps in metabolism of nutrients such as carbohydrates, proteins, and lipids.
(ii) Detoxification of harmful substances in the body
(iii) It produces bile which aids in the digestion and absorption of fats in the small intestine.
(iv) It helps regulate blood glucose levels and stores glycogen for future energy needs.
(v) The liver stores essential vitamins like vitamins A, D, B12) and minerals like iron and copper, releasing them into the bloodstream as needed.

(4c)
(i) Sustainable Logging Practices: Implementing selective logging techniques and sustainable harvesting limits to avoid overexploitation and allow forests to regenerate naturally.
(ii) Protected Areas and Reserves: Establishing protected areas, national parks, and wildlife reserves to conserve important forest ecosystems and biodiversity.
(iii) Reforestation and Afforestation: Planting new trees in deforested areas (reforestation) and establishing forests in areas that were not previously forested (afforestation) to restore degraded landscapes and increase forest cover.
(iv) Community-Based Conservation: Involving local communities in forest management and conservation efforts to ensure sustainable resource use and foster a sense of responsibility for forest protection.
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(5a)

(5bi)
(PICK ANY TWO)
(i) The calyx, consisting of sepals, provides protection to the developing flower bud.
(ii) The calyx provides additional support to the flower, helping it remain upright and stable during growth and pollination.
(iii) The calyx may also aid in water retention for the flower bud and its developing reproductive parts.
(iv) The calyx's sepals often enclose and protect the delicate reproductive organs within the flower, such as the stamens and pistil.

(5bii)
(i) Insulin
(ii) Testosterone
(iii) Estrogen
(iv) Adrenaline
(v) Thyroxine

(5ci)
(i) Genetic Testing and Counseling: The understanding of heredity and genetics has led to the development of genetic testing to identify individuals at risk of inheriting certain genetic disorders.
(ii) Gene Therapy: Heredity principles have paved the way for advancements in gene therapy. Researchers can manipulate genes responsible for certain diseases, aiming to correct or replace defective genes, which may provide potential cures for genetic disorders.

(5cii)
(i) Many leaves have broad, flat surfaces that maximize the exposure of chloroplast-containing cells to sunlight.
(ii) Thin and transparent cuticle covering the upper epidermis of leaves allows light to penetrate into the leaf tissues.
(iii) Presence of Stomata which enables the exchange of gases, including carbon dioxide required for photosynthesis and oxygen produced during the process.

IMAGE VERSION







C. 2023 NECO BIOLOGY (ESSAY) QUESTIONS:


 

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