WAEC SSCE - Biology - 2022 (Essay)

Bayanin Amsa

Milk teeth, also known as deciduous teeth, baby teeth, or primary teeth, are the first set of teeth that humans develop. These teeth usually start to emerge around 6 months of age and are gradually replaced by permanent teeth from around 6 years old onwards. Milk teeth serve several important functions, including aiding in speech development, facilitating proper chewing and digestion of food, and holding space in the jaw for the eventual eruption of permanent teeth. Milk teeth are smaller and whiter in color than permanent teeth and have thinner enamel, which makes them more prone to decay and cavities. It is important to take care of milk teeth by brushing them regularly and limiting sugary foods and drinks to help prevent tooth decay. In summary, milk teeth are the first set of teeth that humans develop, which serve important functions for proper chewing and digestion of food, speech development, and holding space for permanent teeth.

Bayanin Amsa

(a)(i) A cell is the basic structural and functional unit of life; it is the smallest unit capable of carrying out all the activities necessary for the survival of a living organism.

(a)(ii) Three scientists associated with the discovery of the cell are:

• Robert Hooke
• Anton van Leeuwenhoek
• Matthias Schleiden

(b)(i) A labelled diagram of a plant cell (drawn 6 cm to 8 cm long), with the nucleus - the organelle responsible for cell reproduction (cell division) - clearly labelled, is shown below.

The blood cell in humans that does not possess the nucleus is the red blood cell (erythrocyte). The mature mammalian red blood cell has no nucleus.

(b)(iii) Because the red blood cell has no nucleus, it lacks the DNA that controls cell division. The biological implications are:

• It cannot divide, reproduce or replace itself, so it has a short, limited lifespan (about 120 days) and must be continually replaced by new cells made in the red bone marrow.
• It cannot repair itself or synthesise new proteins and enzymes once damaged.
• The absence of the nucleus creates more internal space for haemoglobin, increasing the cell's oxygen-carrying capacity.

(c) Six organelles found in a plant cell:

1. Nucleus
2. Chloroplast
3. Mitochondrion
4. Endoplasmic reticulum
5. Golgi apparatus
6. Ribosome

Bayanin Amsa

Bayanin Amsa

1.(a) Classification of specimens A and C according to thier lifecycle
         A: Annual/perennial
        C: Annual

     b)  Observable diferences between specimens
         A and C

Ways by which the damage to specimen A could have been prevented
Storage in air-tight containers/vacuum seal the bean seeds/add oxygen absorber

i. Use of pesticides/fumiganting/secticide

ii. Freezing

iv. Irradiation/radiation of seeds

v.Hygienic storage on sanitation

d) Type of germination of specimens A and C when planted 
A: Epigeal
C: Hypogeal

[ei]Drawing/diagram of longitudinal section
L.S.)of specimen C/maize grain

Bayanin Amsa

(a)(i) habitats of specimens of D and E

        D:     Termatarium/anthill/old logs of trees/mounds dead tree stumps

        E:      nest/hive

(ii) observable structural differences between specimens D and E

[iii] (iii) Behavioural adaptation common1o specimens D and E
Social insects/nuptial flight/swarming

(b) Economic importance of specimen E

a. Production of honey

b. Production of beeswax/wax

c. Pollinating agent d. Employment

e. Their stings lead to allergies/anaphylactic shock/difficulty in breathing/rashes/skin irritations

f. Their stings could lead to death.

{c} Table

d[i]  mode of feeding specimens G herbivorous

  ii   ways by which specimen G adapts its organism to its mode of feeding

 a.   sharp/chisel shaped/curved incisors for cutting vegetation/leaves /food/gnawing/bibbling/bitting

 b.    broad/ridged surface of premolar ; for grinding /chewing 

Presence of  diastema/space between incisor
grinding/chewing and premolar, allows the rolling of food into bolus/its separates.freshly cut food/grass from the one being chewed.

e.Mineral element needed for the proper functioning of specimen G

 i.Calcium           ii. Phosphorus  iii. Copper
 iv.Boron             v. Zinc              vi. Copper

 vii.Magnesium   viii. Iron           ix. Potassium

Bayanin Amsa

(a) Ecological niche: An ecological niche refers to the specific role and position that an organism occupies within an ecosystem. It includes the interactions and relationships of the organism with its environment, including other organisms, resources, and physical factors. Essentially, the ecological niche describes how an organism fits into its ecosystem and the functions it performs within that system. (i) Roles played by a mango tree in its ecological niche: 1. Primary producer: Mango trees are photosynthetic organisms, converting sunlight into chemical energy through photosynthesis. They produce organic compounds (such as sugars) using carbon dioxide, water, and sunlight. 2. Habitat provider: Mango trees provide shelter and habitat for various organisms such as birds, insects, and small mammals. They offer nesting sites, food sources, and protection from predators. 3. Oxygen producer: Through photosynthesis, mango trees release oxygen into the atmosphere, contributing to the oxygen supply necessary for many organisms to survive. 4. Food source: Mango trees bear fruit, which serves as a food source for animals, including humans. The fruits provide nourishment and contribute to the diet and survival of many organisms. 5. Soil stabilization: The roots of mango trees help prevent soil erosion by binding the soil particles together, reducing the risk of landslides and maintaining the stability of the surrounding environment. (b) Ecologists use sampling techniques in population studies for two main reasons: (i) Reasons for using sampling techniques in population studies: 1. Practicality: It is often impossible or impractical to study an entire population due to factors such as time, cost, or logistics. Sampling allows ecologists to gather data from a representative subset of the population, providing insights into the larger population as a whole. 2. Accuracy: When properly designed and executed, sampling techniques can provide accurate and reliable information about a population. By collecting data from a well-selected sample, ecologists can make inferences and draw conclusions about the population with a reasonable level of confidence. (i) Examples of sampling techniques used in population studies: 1. Random sampling: This involves randomly selecting individuals from the population, ensuring that each member has an equal chance of being chosen. It helps to avoid bias and provides a representative sample. 2. Stratified sampling: This technique involves dividing the population into subgroups or strata based on specific characteristics and then randomly selecting individuals from each subgroup. It ensures representation from different groups within the population. (c) Types of fingerprints in humans: The four main types of fingerprints in humans are: 1. Loop: This type of fingerprint forms ridges that enter from one side, curve, and exit from the same side. It resembles a loop shape. 2. Whorl: Whorl fingerprints have ridges that form circular or spiral patterns. They have at least one ridge that makes a complete circuit. 3. Arch: Arch fingerprints have ridges that enter from one side and exit from the other side, forming a slight rise in the center. They do not make loops or circles. 4. Composite: Composite fingerprints are a combination of two or more of the above types. They may exhibit characteristics of both loop and whorl, or loop and arch patterns. (d) The plant used by Gregor Mendel in his experiment: The plant used by Gregor Mendel in his experiments on inheritance and genetics was the garden pea plant, scientifically known as Pisum sativum. (ii) Reasons why the garden pea plant was used: 1. Easy to cultivate: The garden pea plant is relatively easy to grow and cultivate, allowing for large-scale experiments and the controlled breeding of different varieties. 2. Observable traits: The garden pea plant exhibits distinct and easily observable traits, such as flower color (purple or white), seed shape (round or wrinkled), and plant height (tall or short). These traits

Bayanin Amsa

(a) Conservation laws are fundamental principles in physics that state that certain physical properties, such as energy, momentum, and angular momentum, are conserved during interactions between particles or objects. (i) Three conservation laws are: 1. The conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. 2. The conservation of momentum, which states that the total momentum of a system remains constant unless acted upon by an external force. 3. The conservation of angular momentum, which states that the total angular momentum of a system remains constant unless acted upon by an external torque. (b) Two reasons why animals are poached are for their valuable parts such as ivory, fur, and organs, and for use in traditional medicines or cultural practices. (i) Five animals that are commonly poached are: 1. Elephants for their ivory tusks 2. Rhinoceroses for their horns 3. Tigers for their fur and bones 4. Pangolins for their scales and meat 5. Gorillas for their meat and body parts (c) Four effects of excessive use of the forest are: 1. Deforestation, which can lead to habitat loss and a decrease in biodiversity. 2. Soil erosion, which can cause landslides and decreased soil fertility. 3. Climate change, as forests absorb carbon dioxide and release oxygen, and their removal can contribute to increased greenhouse gas emissions. 4. Disruption of water cycles, as forests play a key role in regulating water flow and maintaining water quality. (d) i. Blood transfusion is the process of transferring blood or blood products from one person (the donor) into the bloodstream of another person (the recipient). It is often used in medical emergencies, such as to replace blood lost during surgery or trauma, or to treat certain medical conditions such as anemia. ii. An antigen is a substance that is capable of eliciting an immune response in the body, such as by causing the production of antibodies. In the context of blood transfusions, antigens are found on the surface of red blood cells and can cause an immune response if they are not compatible with the recipient's blood type. This can lead to complications such as hemolysis, a breakdown of red blood cells. Matching blood types between donor and recipient is crucial to avoid these complications.

Bayanin Amsa

(a)

(i) Specimens H and L

1. H has a short, stout, conical beak, whereas L has a long, slender, pointed beak.
2. H has strong feet with claws suited for scratching the ground, whereas L has feet adapted mainly for perching.

(ii) Specimens K and M

1. K has fins, whereas M has paddle-like flippers.
2. K has a scaly body covering, whereas M has a smooth skin without scales.

(b)(i) Adaptations

Specimen	Adaptive features
H	Its short, strong conical beak is used for picking and cracking seeds. Its strong clawed feet enable it to scratch the ground in search of food.
M	Its streamlined body reduces resistance while moving in water. Its flippers and powerful tail aid swimming and propulsion.

(b)(ii) The organism possessing specimen H feeds on seeds or grains and insects.

(c) Drawing of specimen K, showing a fish about 8 cm to 10 cm long.

(d) One habitat of the organism possessing specimen K is a freshwater pond.

(e)

Specimen	Feeding habit
H	Granivorous or seed-feeding.
L	Insectivorous.

(f)

(i) H and L: Both have beaks, and both possess feathers and wings.

(ii) K and M: Both have streamlined bodies, and both have tails used in movement through water.

Bayanin Amsa

A herbivore and a carnivore are two types of animals that have different feeding habits. Herbivores primarily eat plants, while carnivores primarily eat other animals. Here are three differences between the definitions of herbivores and carnivores: 1. Feeding Habits: Herbivores are animals that consume only plants, while carnivores are animals that consume only other animals. This means that herbivores have adaptations such as long intestines and specialized teeth for grinding and breaking down tough plant material, while carnivores have adaptations such as sharp teeth and strong jaws for catching and tearing apart their prey. 2. Nutrient Requirements: Herbivores and carnivores have different nutrient requirements. Herbivores need to consume a large quantity of plant material to obtain enough energy and nutrients, including carbohydrates, proteins, and fiber. Carnivores, on the other hand, obtain their energy and nutrients from consuming other animals, which provide them with high-quality protein and fat. 3. Digestive System: Herbivores and carnivores have different digestive systems. Herbivores have a longer digestive tract and more complex digestive system, including a specialized stomach, multiple stomach chambers, and microorganisms in their gut that help break down plant material. Carnivores, on the other hand, have a shorter digestive tract and a simpler digestive system, as they primarily consume meat, which is easier to digest.

Bayanin Amsa

(a) Three differences between the alimentary canals of the earthworm and the cockroach:

Three similarities: both have a mouth, both have a muscular gizzard for grinding food, and both have a complete (one-way) alimentary canal ending in an anus with a distinct crop for storage.

(b)

(i) The biological cycle illustrated is the carbon cycle (carbon dioxide - oxygen cycle).

(ii) Three roles played by plants and animals in the cycle:

• Green plants take in carbon dioxide during photosynthesis and fix it into organic food, removing carbon dioxide from the air.
• Plants and animals release carbon dioxide back into the air during respiration.
• When plants and animals die, their bodies are decomposed, releasing carbon dioxide; animals also transfer carbon along food chains by feeding on plants.

(iii) Processes: X - photosynthesis, Y - respiration, Z - decay (decomposition) / combustion.

(c) Organs of excretion in humans and diseases affecting them:

(d)

(i) Decay of organic matter is the breaking down of dead plant and animal tissues into simpler substances by the action of micro-organisms.

(ii) Two groups of organisms that cause decay: bacteria and fungi.

(iii) One other factor that causes decay: suitable warmth (temperature); also moisture and oxygen.

(iv) The biological cycle that involves decay: the carbon cycle (and the nitrogen cycle).

(e) Carnivorous plants are green and carry out photosynthesis to make carbohydrates, but they grow in nitrogen-deficient soils. They trap and digest small insects using modified leaves (traps), secreting enzymes that break down the animal protein to obtain nitrogen and other mineral nutrients. Their nutrition is therefore partly autotrophic (photosynthetic) and partly heterotrophic (holozoic on insects).

Bayanin Amsa

[a] 

[b] Differences between a herbivore and a carnivore:

1. Diet: Herbivores primarily consume plant material, such as leaves, grass, and fruits, while carnivores eat mainly meat or animal tissue.

2. Teeth structure: Herbivores typically have specialized teeth for grinding and chewing plant matter, such as flat molars and incisors, while carnivores have sharp teeth, including canines and carnassials, for tearing and cutting flesh.

3. Digestive system: Herbivores have a longer digestive tract to break down and extract nutrients from plant material, while carnivores have a shorter digestive system as they obtain nutrients more easily from animal tissue. Differences between a human and a goat:

1. Anatomy: Humans have an upright posture and bipedal locomotion, while goats have a four-legged stance and quadrupedal locomotion.

2. Diet: Humans are omnivorous and have a diverse diet that includes both plant and animal-based food, while goats are herbivores and primarily graze on vegetation.

3. Communication: Humans have developed complex language systems for communication, while goats primarily communicate through vocalizations, body language, and scent marking.

4. Habitat and lifestyle: Humans have a wide range of habitats and live in diverse social structures, while goats are typically found in specific regions, such as mountains or grasslands, and live in herds.

[c] Milk teeth, also known as deciduous teeth or baby teeth, are the first set of teeth that humans and many other mammals develop. These teeth begin to emerge during infancy and are eventually replaced by permanent teeth as a child grows. Milk teeth play an important role in the early stages of life. They help infants and young children chew and break down food, facilitating proper digestion. These teeth also aid in speech development, as they enable the tongue and lips to make various sounds accurately. Milk teeth are temporary, and as the child grows, they gradually loosen and fall out. This process allows space for the permanent teeth to erupt and take their place. Generally, humans have 20 milk teeth, which include incisors, canines, and molars. The transition from milk teeth to permanent teeth usually occurs between the ages of 6 and 12. During this period, children experience the natural loss of milk teeth and the emergence of their permanent teeth. The permanent teeth are larger, stronger, and meant to last throughout adulthood.

Bayanin Amsa

[c} Human and goat