BIO IO6

GENERAL BIOLOGY II

BY

AISHA MUSTAPHA

DEPARTMENT OF BIOLOGY

FEDERAL UNIVERSITY OF HEALTH SCIENCES, AZARE

(FUHSA)
 KINGDOM PLANTAE

Introduction to the Five Kingdom Classification

The Five Kingdom classification system was proposed by R.H. Whittaker in 1969.

This system classifies all living organisms into five distinct kingdoms based on

several critical features such as:

• Cellular structure (prokaryotic or eukaryotic),

• Mode of nutrition (autotrophic or heterotrophic),

• Body organization (unicellular or multicellular),

• Reproductive methods (asexual or sexual),

• Phylogenetic relationships (evolutionary lineage).

The five kingdoms proposed are:

1. Monera

2. Protista

3. Fungi

4. Plantae

5. Animalia
 KINGDOM PLANTAE

Kingdom Plantae comprises all multicellular, eukaryotic, and autotrophic organisms

commonly referred to as plants. These organisms are highly diverse, ranging from

microscopic algae to massive trees.

Features

1. Multicellular and Eukaryotic: Plant cells possess membrane-bound

organelles and a defined nucleus.

2. Autotrophic Nutrition: They synthesize their own food via

photosynthesis using sunlight, water and carbon dioxide.

3. Presence of Chloroplasts: They contain chlorophyll, the green pigment

essential for capturing light energy.

4. Rigid Cell Wall: The cell wall is made of cellulose. It provides structural

support and protection.

5. Central Vacuole: It helps in maintaining cell turgor pressure and

storage.

6. Non-motile: Plants are generally fixed in one place and do not exhibit

locomotion.

7. Reproduction: Reproduction may be asexual (e.g. vegetative

propagation) or sexual, involving the fusion of male and female gametes.

Criteria for Classification within Kingdom Plantae

The plant kingdom is further subdivided into various groups based on:

1. Plant Body Differentiation

Presence or absence of distinct structures like roots, stems, and leaves.

2. Vascular Tissue

Presence of conducting tissues: xylem (for water and minerals) and

phloem (for food transport).

3. Reproductive Structures

Whether the plant produces seeds or spores, and whether the seeds are

naked or enclosed in fruit.

Classification of the Plant Kingdom

1. Thallophyta

i. They are primitive with simple body structure that has no true roots,

stems or leaves.

ii. The plant body is known as a thallus, which may be filamentous,

branched, unbranched, or colonial.

 iii. They are primarily aquatic. They can be found both in freshwater and

marine environments.

iv. Reproduction can be vegetative, asexual (spores), or sexual.

Examples: Spirogyra, Ulothrix, Chara, Volvox, Fucus, Polysiphonia.

2. Bryophyta

i. They are referred to as the “amphibians of the plant kingdom” because

they need water for reproduction.

ii. They lack true vascular tissues but have structures that resemble roots

(rhizoids), stems, and leaves.

iii. They are usually found in moist and shady terrestrial habitats.

iv. They exhibit a dominant gametophyte generation in their life cycle.

v. They include the mosses, liverworts and hornworts.

Examples: Marchantia, Funaria, Sphagnum, Anthoceros.

3. Pteriadophyta

i. They are the first group of vascular plants (they possess xylem and

phloem).

ii. They have a body differentiated into roots, stems, and leaves.
 iii. They reproduce via spores and do not produce seeds.

iv. They are found in cool, damp, shady environments, though some

species are adapted to dry conditions.

v. The sporophyte is the dominant generation.

Examples: Selaginella, Equisetum (Horsetail), Pteris, Marsilea.

4. Gymnospermae

i. They have a well-differentiated plant body and advanced vascular

tissues.

ii. They produce seeds, but the seeds are naked, not enclosed within a fruit.

iii. They are mostly woody, perennial and can form large trees.

iv. They are mostly wind-pollinated and reproduce sexually.

Examples: Pinus, Cycas, Ephedra, Ginkgo

5. Angiospermae

i. These are largest and most diverse group of plants.

ii. They bear flowers and seeds enclosed within fruits.

iii. They have a highly developed vascular system and a well-differentiated

body.
 iv. They can range in size from tiny herbs (e.g. Wolffia) to massive trees

(e.g. Eucalyptus).

v. The seeds develop within the ovary, which matures into the fruit.

vi. They reproduce primarily through sexual reproduction.

vii. They are divided into two main groups based on the number of seed

leaves (cotyledons):

• Monocotyledons (Monocots) – One cotyledon (e.g. maize, onion,

wheat).

• Dicotyledons (Dicots) – Two cotyledons (e.g. mango, rose, tomato).

Classification of Kingdom Plantae

Body Vascular Mode of Seed

Division Differentiation Tissues Reproduction Formation

Thallophyta No No Spores No

Bryophyta Yes No Spores No

Pteridophyta Yes Yes Spores No

Gymnospermae Yes Yes Seeds Yes

Angiospermae Yes Yes Seeds Yes

Life Cycle of Plants and Alternation of Generations

One of the most important biological processes in the plant kingdom is the

alternation of generations, also known as haplodiplontic life cycle.

Alternation of generations refers to a reproductive cycle in which two distinct

multicellular stages alternate:

1. Gametophyte (n) – Haploid generation that produces gametes (sperm

and egg).

2. Sporophyte (2n) – Diploid generation that produces spores through

meiosis.
General Steps in the Plant Life Cycle:

1. Gametophyte (n) produces haploid gametes by mitosis.

2. Fertilization: Fusion of male and female gametes forms a diploid zygote

(2n).

3. Zygote develops into a sporophyte (2n).

4. Sporophyte produces haploid spores via meiosis.

5. Spores germinate and grow into new gametophytes (n).

6. The cycle continues.

Types of Life Cycles in Plants

1. Haplontic: Gametophyte is dominant; sporophyte is unicellular and

short-lived

• Seen in Thallophytes (e.g., Chlamydomonas, Spirogyra)

2. Diplontic: Sporophyte is dominant; gametophyte is reduced and short-

lived

• Seen in Gymnosperms and Angiosperms

3. Haplodiplontic: Both gametophyte and sporophyte are multicellular;

one may be dominant

• Seen in Bryophytes and Pteridophytes

• Bryophytes: Dominant gametophyte

• Pteridophytes: Dominant sporophyte

Alternation of Generations

Gametophyte (n)

/ \

Male Gamete Female Gamete

\ /

Fertilization

Zygote (2n)

Sporophyte (2n)

Spore mother cells

Meiosis

Spores (n)

Germination

New Gametophyte (n)

Alternations of Generations in Major Plant Groups

Dominant

Plant Group Generation Type of Life Cycle

Thallophyta Gametophyte Haplontic

Bryophyta Gametophyte Haplodiplontic

Pteridophyta Sporophyte Haplodiplontic

Gymnospermae Sporophyte Diplontic

Angiospermae Sporophyte Diplontic

 ALGAE

Algae are a diverse group of primarily aquatic, photosynthetic organisms that range

in complexity from microscopic unicellular forms e.g., Chlorella, Diatoms to large

multicellular forms like giant kelps. The body of algae is not differentiated roots,

stems, and leaves. Algae perform oxygenic photosynthesis using chlorophyll and

play a foundational role in aquatic ecosystems and the global biosphere.

General Characteristics of Algae

1. Photosynthetic Pigments: All algae contain chlorophyll a. Accessory pigments

such as chlorophyll b, c, carotenoids, phycocyanin, and phycoerythrin vary

among groups.

2. Habitat: Algae are found in marine and freshwater ecosystems, on moist soils,

tree trunks, snow, and in symbiotic relationships (e.g., lichens, coral).

3. Cellular Organization: Eukaryotic e.g, Green, brown, red algae, diatoms, etc.

4. Morphology: Unicellular (e.g., Chlamydomonas), colonial (Volvox),

filamentous (Spirogyra), or complex multicellular thalli (Laminaria).

5. Reproduction: Varies among groups:

i. Vegetative (fragmentation),

ii. Asexual (spores, zoospores),

iii. Sexual (isogamy, anisogamy, oogamy).

 6. Life Cycles: Haplontic, diplontic, and haplodiplontic (alternation of

generations).

Classification of Algae

Group Pigments Storage Material

Chlorophyta (Greenalgae) Chlorophyll a, b Starch

Phaeophyta (Brownalgae) Chlorophyll a, c, fucoxanthin Laminarin, mannitol

Rhodophyta (Red algae) Chlorophyll a, d,phycoerythrin Floridean starch

Bacillariophyta Chlorophyll a, c, fucoxanthin Oil, leucosin

Dinoflagellata Chlorophyll a, c, peridinin Starch, oil

Ecological Importance of Algae

1. Primary Production

i. Algae, especially phytoplankton, contribute nearly half of the global

photosynthetic output.

ii. Support aquatic food webs by serving as the primary producers in both

freshwater and marine environments.

2. Oxygen Generation

i. Algae are responsible for producing over 50–70% of the Earth’s oxygen,
 especially via marine phytoplankton.

ii. Major contributors to atmospheric O₂ and oceanic oxygenation.

3. Carbon Sequestration

i. Algae play a crucial role in removing atmospheric CO₂ through

photosynthesis.

ii. Marine algae participate in the biological carbon pump, sinking carbon to

ocean depths when they die.

4. Nutrient Cycling

i. Algae facilitate nutrient turnover, especially nitrogen and phosphorus, by

absorbing these from water and releasing them through decomposition.

5. Habitat Formation

i. Large algae like kelps form underwater forests, providing habitat and

protection for fish, invertebrates, and marine mammals.

6. Bioindicators of Pollution

i. Algal species composition is sensitive to water quality changes.

ii. Eutrophication often leads to harmful algal blooms (HABs), which serve

as early indicators of nutrient overload.

7. Symbiotic Roles

i. Algae form symbiotic relationships with fungi (lichens), corals

(zooxanthellae), and protozoa, facilitating ecosystem stability and

 productivity.

Economic Importance of Algae

1. Food and Nutrition

i. Edible algae like Porphyra (nori), Laminaria (kombu), and Ulva (sea

lettuce) are traditional food sources in many cultures.

ii. Microalgae like Spirulina and Chlorella are marketed as “superfoods” for

their protein, antioxidants, vitamins, and essential fatty acids.

2. Hydrocolloids and Industrial Extracts

i. Agar (from Gelidium, Gracilaria): used in microbiology, food gelling, and

cosmetics.

ii. Alginates (from Macrocystis, Laminaria): used in food thickening,

pharmaceuticals, and textiles.

iii. Carrageenan (from Chondrus crispus): used in dairy and meat products

for texture and stabilization.

3. Biofuels

i. Algae are a leading candidate for third-generation biofuels due to high

growth rates and high oil/lipid content.

ii. Potential products: biodiesel, bioethanol, methane, hydrogen.

4. Agriculture and Soil Enrichment

i. Seaweed extracts improve crop growth, yield, resistance to drought and

 pests.

ii. Enhance soil structure and microbial activity.

5. Pharmaceuticals and Biomedicine

i. Algae synthesize bioactive compounds with antiviral (e.g., against herpes,

HIV), antibacterial, anticancer properties.

ii. Some species are being researched for wound dressings and drug delivery

systems.

6. Aquaculture and Animal Feed

i. Microalgae are used to feed larval fish, mollusks, and crustaceans.

ii. Added to livestock feed for nutritional enrichment and immune support.

7. Bioplastics and Bioproducts

i. Algae are being developed into sustainable, biodegradable plastics and

packaging to reduce reliance on petroleum-based materials.

8. Environmental Applications (Bioremediation)

i. Algae are used in wastewater treatment for removing heavy metals and

toxins and also biofiltration and nutrient stripping.

ii. Algal ponds serve as low-cost treatment options in rural and developing

areas.
 ECOLOGICAL ADAPTATION

Ecological adaptation refers to any heritable structural, physiological, or behavioral

characteristic that enhances the ability of an organism to survive, reproduce, and

thrive in a specific habitat or ecosystem. It is a long-term evolutionary process by

which organisms become better suited to their environment through natural

selection. Adaptation allows organisms to deal with environmental challenges such

as extreme temperatures, scarce food or water availability, predation pressures, or

competition for resources.

TYPES OF ECOLOGICAL ADAPTATION

Organisms exhibit various kinds of adaptations depending on the challenges they

face in their environments. These adaptations are generally grouped into three main

categories:

1. Structural (Morphological) Adaptations

These are physical features or modifications in the body structure of an organism

that enhance its survival and reproductive success. Such adaptations may involve the

size, shape, color, external appendages, or internal anatomy of an organism.

Examples include:

i. The streamlined body of fish that aids efficient swimming.

 ii. Thick fur and blubber in polar animals like polar bears and seals to insulate

against freezing temperatures.

iii. Cacti having thick, fleshy stems to store water, spines to reduce water loss

and deter herbivores.

2. Physiological Adaptations

These adaptations involve internal body processes that help organisms function

optimally under specific environmental conditions. They include biochemical and

metabolic changes that are not always visible externally.

Examples include:

i. The ability of desert animals such as camels to conserve water by

producing concentrated urine and tolerating high body temperatures.

ii. Venom production in snakes as a mechanism for defense or predation.

iii. Regulation of body temperature (thermoregulation) in endothermic

animals such as mammals and birds.

iv. The ability of some plants to perform photosynthesis using specialized

pathways (e.g., CAM and C4 metabolism) in arid environments.

3. Behavioral Adaptations

These are observable actions or behavioral traits that organisms develop to survive

in their habitats. Behavioral adaptations may be innate or learned and usually

enhance feeding, mating, predator avoidance, or migration.

Examples include:

i. Migration of birds (e.g., Arctic Tern) to favorable climates for breeding

and food availability.

ii. Hibernation in bears and aestivation in desert snails to avoid extreme

temperatures or drought.

iii. Mating displays, such as the elaborate feather display of peacocks to attract

mates.

ADAPTATIONS IN ANIMALS

Adaptations in Desert Animals

Desert habitats are characterized by low rainfall, high diurnal temperature

fluctuations, and limited vegetation. Animals in such habitats must cope with water

scarcity, intense heat, and limited food supply.

Key adaptations include:

i. Water Conservation: Camels have evolved to survive without water for

several days. They minimize sweating and have a specialized metabolism

 that allows them to tolerate dehydration.

ii. Nocturnality: Many desert animals are nocturnal (e.g., jerboas, foxes),

meaning they are active during the cooler night to avoid daytime heat and

reduce water loss.

iii. Specialized Excretion: Birds and reptiles excrete uric acid, which requires

less water than urea, thus conserving body moisture.

iv. Thermoregulatory Features: Large ears in animals like jackrabbits act as

radiators to dissipate body heat through blood vessels close to the skin

surface.

v. Behavioral Strategies: Burrowing during the day, resting under rocks, and

living in shaded crevices are common behaviors for temperature

regulation.

Adaptations in Grassland Animals

Grasslands are open ecosystems dominated by grasses, with few trees. They are

home to fast-running animals and predators with keen senses.

Adaptations include:

i. Speed and Agility: Cheetahs, antelopes, and pronghorns have long limbs

and lightweight bodies for rapid movement, necessary for both hunting and

evasion.
 ii. Camouflage: Many grassland animals have coats that blend with the dry,

yellowish grass to avoid detection by predators (e.g., lions, deer).

iii. Digestive Adaptations: Herbivores like bison and zebras have complex

digestive systems (e.g., multi-chambered stomachs) for breaking down

cellulose in grasses.

Adaptations in Tropical Rainforest Animals

Tropical rainforests are dense, biodiverse ecosystems with high humidity and

consistent rainfall. Animals here must adapt to vertical living and intense

competition.

Notable adaptations:

i. Camouflage and Mimicry: Insects and frogs often resemble leaves or tree

bark (e.g., leaf insects, tree frogs). Some butterflies mimic toxic species to

avoid predation.

ii. Arboreal Lifestyle: Many animals like monkeys and sloths have prehensile

tails, strong limbs, and grasping hands adapted for tree-dwelling.

iii. Sound Communication and Coloration: Bright colors and loud calls help

animals like birds and frogs attract mates or ward off predators.
Adaptations in Polar Animals

Polar ecosystems are extremely cold, with long winters, short summers, and limited

vegetation. Only specially adapted animals can survive here.

Examples include:

i. Thick Fur and Fat Layers: Polar bears and arctic foxes have thick

insulating fur. Marine mammals have blubber to provide insulation and

energy reserves.

ii. Coloration: White fur or feathers offer camouflage in the snow and help

animals sneak up on prey or hide from predators.

iii. Reduced Extremities: Smaller ears and tails help reduce heat loss through

extremities (Allen’s rule).

iv. Seasonal Behavior: Animals may migrate, hibernate, or go into torpor to

conserve energy during harsh winter conditions.

PLANT ADAPTATIONS

Plants, though sessile, display a remarkable array of adaptations to survive in diverse

environments ranging from arid deserts to frigid polar zones and aquatic habitats.
Desert Plant Adaptations

i. Water Storage: Succulents like cacti store water in their fleshy stems and

leaves.

ii. Reduced Leaves: Leaves are modified into spines to minimize

transpiration and reduce water loss.

iii. Deep or Widespread Roots: Roots penetrate deep into the soil to access

underground water or spread widely to capture rain quickly.

iv. Waxy Cuticles: A thick, waxy layer on leaves reduces evaporation.

v. Dormancy: Seeds of some desert plants remain dormant during dry spells

and germinate only after rain.

Tropical Rainforest Plant Adaptations

i. Competition for Light: Tall trees grow rapidly to reach sunlight, forming a

dense canopy. Understory plants have large, broad leaves to capture limited

light.

ii. Drip Tips: Leaves often have pointed tips to allow excess rainwater to run

off quickly and prevent fungal growth.

iii. Epiphytic Lifestyle: Plants like orchids and bromeliads grow on trees to

access sunlight and moisture without rooting in the soil.

Aquatic Plant Adaptations

i. Floating Leaves: Plants like water lilies have broad, flat leaves that float

on water and are coated with wax to repel water.

ii. Reduced or Modified Roots: Since water and nutrients are abundant, roots

are often small or serve only anchorage.

iii. Air Spaces (Aerenchyma): Spongy tissues in stems and leaves facilitate

buoyancy and gas exchange.

Polar Plant Adaptations

i. Low Growth Forms: Plants grow close to the ground to avoid wind and

conserve heat.

ii. Hairy and Dark-Colored Leaves: These trap heat and reduce transpiration.

iii. Short Growing Seasons: Plants flower quickly during brief summer

months.

Anti-Herbivory Adaptations in Plants

To avoid being consumed by herbivores, many plants have evolved:

i. Mechanical Defenses: Thorns, spines, and tough leaves deter grazers.

ii. Chemical Defenses: Production of toxic, bitter, or irritating compounds

(e.g., alkaloids, tannins, latex).

iii. Mimicry and Camouflage: Some plants mimic inedible objects or others
may blend with surroundings to avoid detection.
 EXCRETION AND EXCRETORY ORGANS IN HUMANS

Excretion is defined as the biological process through which an organism removes

waste products of metabolism and other non-useful substances from its body. This

process is essential for the survival and proper functioning of all living organisms,

including humans. Metabolic reactions, especially those involved in cellular

respiration, protein catabolism, and other biochemical processes, produce waste

substances. If these wastes accumulate within the body, they can become toxic,

disrupt normal cellular activities, and threaten homeostasis; the stable internal

environment required for optimal biological functioning.

The human body has developed specialized organs and systems to carry out

excretion efficiently. These organs eliminate different types of waste products,

including nitrogenous compounds like urea and uric acid, gaseous waste like carbon

dioxide, and excess salts and water. The process of excretion not only removes

harmful by-products but also plays a crucial role in regulating body fluid volume,

electrolyte concentration, and acid-base balance, thereby contributing to the

maintenance of internal equilibrium.

Major Metabolic Waste Products

The primary waste products that must be excreted from the human body include:

1. Carbon dioxide (CO₂): Produced during aerobic cellular respiration in

body cells; expelled primarily through the lungs.

2. Ammonia (NH₃): A highly toxic compound generated during the

breakdown of amino acids; quickly converted to urea by the liver.

3. Urea: A less toxic nitrogenous compound resulting from the conversion

of ammonia; excreted in urine by the kidneys.

4. Uric acid: Formed during the catabolism of nucleic acids (DNA and

RNA); also excreted through urine.

5. Water and salts: Excess amounts are excreted to maintain osmotic and

electrolyte balance.

6. Bilirubin: A yellow-brown pigment derived from the breakdown of

hemoglobin in old red blood cells; eliminated via bile in the feces.

THE EXCRETORY SYSTEM

Unlike other systems in the human body where organs function in a closely

coordinated manner (e.g., the circulatory or nervous system), the organs of the

excretory system function relatively independently. Each organ specializes in

removing specific types of waste. However, collectively they ensure that the internal

environment remains stable and non-toxic.

The main excretory organs in humans include:

1. The Skin

2. The Liver

3. The Large Intestine

4. The Lungs

5. The Kidneys

1. The Skin

Though primarily an organ of protection and sensation (as part of the integumentary

system), the skin also plays a secondary role in excretion. Sweat glands embedded

within the dermis secrete sweat, a fluid composed mainly of water, salts (primarily

sodium chloride), and small amounts of urea and other metabolic wastes.

Function in Excretion:

i. Sweat removes excess water, sodium, and other electrolytes.

ii. Eliminates minor quantities of nitrogenous wastes like urea and ammonia.

iii. Homeostatic Role: Sweating plays a key role in thermoregulation, helping

to cool the body through evaporation.

iv. Excessive sweating (as in hot climates or during physical activity) can lead

to dehydration, necessitating the intake of water and electrolytes to restore

 balance.

2. The Liver

The liver is a multifunctional organ with significant roles in metabolism,

detoxification, storage, and synthesis. It is also a vital excretory organ, primarily due

to its function in detoxifying harmful substances and transforming toxic nitrogenous

wastes into forms that can be safely excreted.

Excretory Functions:

i. Converts toxic ammonia (from amino acid deamination) into urea, a less

harmful substance that is transported via the bloodstream to the kidneys.

ii. Produces bile, which contains bilirubin, a waste pigment resulting from the

breakdown of red blood cells.

iii. Detoxifies various substances such as alcohol, drugs, and environmental

toxins, preparing them for elimination.

Bile and Excretion:

• Bile is secreted into the small intestine and eventually excreted in feces.

• Bilirubin in bile contributes to the brown coloration of feces.

3. The Large Intestine

The large intestine, or colon, is the final segment of the digestive system and is
responsible for absorbing remaining water and electrolytes from indigestible food

matter, as well as forming and storing feces until defecation.

Role in Excretion:

i. Eliminates undigested food residues and indigestible substances (e.g.,

dietary fiber) in the form of solid waste (feces).

ii. Facilitates the excretion of bilirubin and other metabolic waste components

secreted via bile.

iii. Microbial Activity: Hosts a diverse community of gut bacteria that ferment

indigestible carbohydrates and produce gases and certain vitamins. These

bacteria also contribute to the composition of fecal matter.

4. The Lungs

The lungs, primary organs of the respiratory system, are also crucial for the excretion

of gaseous waste products, particularly carbon dioxide.

Excretory Role:

i. Expel carbon dioxide; a by-product of aerobic respiration, by facilitating

its diffusion from the bloodstream into the alveoli and out through

exhalation.

ii. Eliminate water vapor and small traces of volatile substances with every

breath.
 iii. Physiological Relevance: Help maintain the acid-base balance (pH) of the

blood. Increased CO₂ levels lower blood pH, which in turn stimulates the

respiratory centers in the brain to increase the rate and depth of breathing.

The regulation of breathing rate is thus tightly connected to the levels of

CO₂ and hydrogen ions in the blood.

5. The Kidneys

The kidneys are the principal organs of the urinary system and are considered the

most important excretory organs in the human body due to their role in removing a

wide range of metabolic wastes from the blood.

Structural and Functional Unit: The nephron, of which each kidney contains about a

million, filters blood, reabsorbs useful substances, and secretes wastes into urine.

Main Functions:

i. Filter urea, uric acid, creatinine, and excess ions and water from the blood

to form urine.

ii. Regulate fluid and electrolyte balance (e.g., sodium, potassium, calcium).

iii. Maintain blood pressure through fluid volume regulation and secretion of

renin.

iv. Control acid-base balance by excreting hydrogen ions and reabsorbing

bicarbonate.
 v. Act as endocrine organs, producing:

• Erythropoietin; stimulates red blood cell production in bone marrow.

• Calcitriol; active form of vitamin D, which regulates calcium

absorption.

• Renin; involved in the renin-angiotensin-aldosterone system for blood

pressure regulation.