Subject : 

Biology

Topic :

Adaptation in Form and Functions of Living Organisms Due to Environmental Conditions

Term :

Second Term

Week:

Week 10

Class :

SSS 2

 

Previous lesson : 

The pupils have the previous knowledge of

ECOLOGICAL MANAGEMENT TOLERANCE

that was taught in the last lesson

 

 

Behavioural objectives :

At the end of the lesson, the pupils should be able to

• explain adaptation
• say the variation in plant and animals due to changes in environment
• State three structural adaptations of tadpole to aquatic life.
• State three structural adaptations of birds to their feeding habits.

 

Instructional Materials :

 

• Poster
• Wall Chart
• News paper
• Online Video
• Pictures

 

 

Methods of Teaching :

• Class Discussion
• Group Dialogue
• Asking Questions
• Explanation
• Role Modelling
• Role Delegation

 

Reference Materials :

• Scheme of Work
• Online Information
• Textbooks
• Workbooks
• 9 Year Basic Education Curriculum
• Workbooks

 

 

Adaptation in Form and Functions of Living Organisms Due to Environmental Conditions

Adaptation refers to any feature or characteristics possessed by an organism that contributes to its fitness and survival in its environment. In order to survive and fit into their environment, living organisms usually possess some adaptive features that make them to withstand life-threatening and unfavourable environmental conditions and promote their well-being and proliferation.

Adaptations are inherited characteristics of organisms. They are display in three main features of organisms, their physiology and their behaviour. Some insects mimic leaves in order to escape predators, while some plants produce toxins, which prevent other plants from growing near them, thus reducing competition.

Stems

The stem of a plant provides pathways for the distribution of water and nutrients between the roots, leaves, and other parts of the plant. The herbaceous stem of the dandelion (top, center) lacks lignin, the stiffening material in rigid, supportive woody stems. For this reason, herbaceous plants are generally limited in their physical size. Spurges and cacti (bottom, left), their leaves reduced to needles to prevent evaporation in a dry climate, consist entirely of stem material. Tubers, such as potatoes (top, right), are swollen, food-storing, underground stems that nourish growing buds. The stems of some plants are adapted for protection, as in the hawthorn (bottom, right). Others actively compete for sunlight, using touch-sensitive, curling tendrils (top, left) or other structures to climb upwards.

Adaptation of Plants

Plants are grouped into three on the basis of the environmental conditions under which they grow, especially on availability of water in the soil. The three groups are hydrophytes, mesophytes and xerophytes.

Adaptation of Hydrophytes

Hydrophytes are plants that have adapted to living in the aquatic environment. They are either submerged of floating on the water surface. The plants can also grow in the soil that is permanently saturated with water. Their adaptive features include the following:

1. Possession of large air cavities called parenchyma that serve as a means of buoyancy and storing gases for respiration.
2. Possession of photosynthetic chloroplast that make use of less light in water for photosynthesis.
3. Possession of breathing roots (pneumatophores) by some of the hydrophytes, which grows above the water level to get enough oxygen for respiration.
4. Possession of hairy leaves and thin and waxy cuticle to repel rain water as they do not meet it.
5. Surface plants float on water have broad leaves that contain numerous stomata on the upper side of the leaf, which trap maximum light for photosynthesis.
6. Possession of small feathering roots.
7. Less rigid structure because water pressure support them.
8. They have succulent stem.
9. Numerous stomata are opened at all times.

Examples of hydrophytes include water lily, water lotus and water hyacinth.

Adaptation of Mesophytes

Mesophytes are terrestrial plants that grow in areas of moderate water supply. They are the large ecological group of terrestrial plants. Their adaptive features are:

1. Possession of well developed root system.
2. Presence of well developed vascular bundle.
3. Possession of large thin leaves.
4. Presence of large number of stomata on the under surface of the leaves.
5. Presence of erect and branded stem.
6. Possession of mesophyll layer that is well differentiated with many intercellular spaces.[mediator_tech]

Examples include maize, sunflower, cassava, hibiscus, mango and orange.

Adaptation of Xerophytes

Xerophytes are plants that grow in dry areas with little water or moisture such as desert. Their adaptive features are:

1. Reduced leaves that are reduced to spines and tiny scales to reduce water loss.
2. Reduced number of stomata to reduce water loss.
3. Sunken stomata reduce transpiration.
4. Large hairs on surface to reduce water loss.
5. Succulent leaves and stems to store water.
6. Deep root system to absorb water from depth.
7. Possession of thick, waxy cuticle that reduces water loss through cuticular transpiration.
8. Shedding of leaves during day season to prevent water loss through transpiration.
9. Possession of ability to fold their leaves during the day to decrease the number of stomata that is exposed, thus reducing the rate of transpiration.

Examples are cactus, euphorbia, Aacia, pine and opuntia.

Jeweled Lizard

This beautiful species also goes by the name of eyed lizard, Lacerta lepida, not because it has eyes, although of course it does, but for the ocelli (“little eyes”), or ringed spots, that adorn its back and flanks. Native to southern Europe and northwestern Africa, the eyed lizard is the largest member of a group of rather unspecialized Old World lizards. The oldest males may reach 80 centimeters (30 inches) from nose to tail tip. Better known to many Europeans are two smaller members of the genus, the wall lizard and the common or live-bearing lizard, which has the unusual habit of producing its young not in the leathery-shelled eggs typical of reptiles but in a thin membrane whose confines they immediately tear out of to assume life as full-fledged lizardlings.

Adaptation of Animals to Terrestrial Habitat

1. Most terrestrial organisms possess well developed supporting or skeletal systems.
2. The flight birds and mammals possess light skeleton to enable them swing in the air.
3. The climbing animals possess long curved claws for support or nuptial pads to help them grip surfaces.
4. Some grassland and desert animals exhibited protective colouration to prevent easy detection by predators or prey e.g. chameleons.
5. The herbivores grace on a variety of forage.
6. Most weak animals possess keen eyesight and can run fast to escape from their predators.
7. They have well developed sense organs.
8. Some possess impermeable coverage to prevent water loss e.g. monitor, lizard and ant eater.

Adaptation of Animals to Aquatic Environment

1. Possession of streamlined body that reduce friction during movement in water e.g. fishes.
2. Possession of dense, waterproof feathers that keep cold water away from bird’s skin and prevent wetting of feather e.g. birds.
3. Possession of webbed feet, formed from their skin between the toes that work like paddles e.g. ducts.
4. Possession of gills in fishes and tad poles for gaseous exchange.
5. Possession of hooks, suckers, sticky under surfaces by stationary organisms for attachment to rock surface e.g. snails, flatworms.
6. Possession of swim bladder to aid buoyancy in water e.g. Tilapia fish.

Bonito

Bonito, a relative of the tuna and mackerel, are buit for speed. Bonitos have streamlined, torpedo-shaped bodies that taper to a thin junction with a large, forked tail.

EVALUATION

1. What is adaptation?
2. Name three forms of adaptation that are notable in organisms.
3. Define the following and give two examples of each: (a) hydrophytes (b) mesophytes (c) xerophytes
4. State five ways by which xerophytes adapt themselves to arid condition.
5. List five ways animals adapt to terrestrial habitat.

 

Effects of Availability of Water on Adaptive Modification

All terrestrial organisms face he problem of water loss from their body fluids to the environment. The body fluids of these organisms are maintained by specialized by osmoregulation or excretory organs such as malphighian tubules and kidney. A balance must be achieved between the amount of water lost and gained.

Many aquatic organisms especially those fresh water environment have their body fluids more concentration than their surroundings and as such gain water by osmosis. In order to minimise this, they have impermeable outer covering. On the other hand, those with body fluids less concentrate than their surrounding would lose water to their environment. The water lost is replaced by drinking much water from the environment.

Structural Adaptation of Tadpole and Fish to Aquatic Life

1. Possession of stream-lined body without neck that enhance movement in water.
2. Possession of a trial fin, which aid in changing of reduction during swimming.
3. Presence of external gills, which serve as the respiratory organ used for oxygen uptake in water.

Becoming a Frog

The legless tadpoles that hatch from a floating mass of frog eggs are the animal’s fishlike larval stage. Part of a true metamorphosis, they have gills and a tail, both of which disappear as the tadpole feeds and grows. When limbs and air-breathing lungs develop, the young frog, now a miniature replica of its parents, emerges from water to land.

Structural Adaptation in Birds

1. Seed-eating birds like sparrow, cardinals and weaver birds have short, thick, conical beaks adapted for cracking seeds or nuts.
2. Birds of prey like hawks, eagles and owls have sharp, curved breaks for tearing flesh, they also have strong chawlike feet, which they use to capture and kill their prey.
3. Aquatic birds like duck and seagulls have long, flat beaks adapted for straining small plants and animals from the water and for gripping fish and sieving muddy water for food. They also have webbed feet adapted for swimming.
4. Birds are insect eaters like woodpeckers have beaks that are long and chisel-like for boring into wood to eat insects. Other insect eaters like the nobblers have thin pointed beaks.
5. Some birds like crows have a multi – purpose beak that is adapted to eat fruits, seeds, insects, fishes and other animals.

Ostrich

The ostrich, Struthio camelus, is a bird of the savannas and deserts of Africa. Its closest cousins-the rheas, cassowaries, emu, and kiwis, as well as the extinct moas and elephant birds-also have or had a southern distribution, in South America, Australia, New Guinea, New Zealand, Africa, and Madagascar. How did these species, none of which can fly, spread across these southern continents and islands? In the time before scientists accepted the theory of continental drift and seafloor spreading, the distribution of the ostrich and its relatives was one of the unaccountable mysteries of biogeography. Now it is considered a classic example of the result of the breakup of the former supercontinent of Gondwanaland, over which the ancestor of all these species is believed to have roamed.

 

EVALUATION

1. State three structural adaptations of tadpole to aquatic life.
2. State three structural adaptations of birds to their feeding habits.
3. Classify plants into three groups on the basis of availability of water to the soil in their environment.
4. State five adaptive features of xerophytes to arid environment.
5. List adaptive features of animals to terrestrial habitat.