Ecology and Ecosystems

Ecology and Ecosystems

• Interdependence is when organisms affect each other's survival; e.g., termites and flagellate protozoa exemplify mutualism.
• Ecology is the study of the environment and ecosystems.
• The environment includes the habitat, surroundings, and conditions where a living organism exists.
• Ecosystems consist of living organisms and their physical surroundings.
• Ecosystem components include physical surroundings, living organisms, and non-living factors.
• Artificial ecosystems are man-made, like backyard bird aviaries, dams, and lakes.
• Natural ecosystems occur naturally in the wild, such as freshwater lakes and forests.

Communities

• A community includes all populations of organisms that live and interact in a shared environment.
• These populations consist of plants, animals, fungi, and microorganisms.
• Species within a community interact via predation, competition, mutualism, and symbiosis.
• A balanced community is important for species survival and overall ecosystem health; e.g., forests include trees, birds, insects, fungi, and mammals.

Abiotic and Biotic Features

• A species' surroundings have both living (biotic) and non-living (abiotic) factors.
• Water helps chemical movement and reactions. Rainfall supports plant growth, flowering, and animal movement.
• Temperature affects the rate of chemical reactions; higher temperatures usually mean faster reactions.
• Ectothermic animals get heat from the environment, unlike endothermic animals like humans and kangaroos, which generate internal heat.
• Bushfires can start from lightning or human activity and can help some plants
• Some flowers thrive after fire, as fire causes some plants to drop seeds that germinate after fire due to chemicals in smoke.
• Light is required for photosynthesis, so plants use water, carbon dioxide, and light to produce food, then animals eat plants.
• The amount of light affects plant growth, flowering, and animal behavior.
• Soil varies in mineral content, water-holding ability, and acidity, affecting plant life.
• Loam soils hold more water than sandy soils. Some plants prefer acidic soils, while others prefer alkaline soils.
• Most organisms need oxygen for respiration.
• Oxygen levels in water are affected by temperature, movement, and depth; cold, moving water has more oxygen.

Symbiosis

• Symbiosis describes any relationship between two different organisms; types depend on benefits to each organism.

Competition

• Competition occurs when organisms vie for limited resources such as food, water, living space, mates, and nesting sites.

Parasitism

• Parasitism is when one organism lives on or in another, benefiting and harming the host; the parasite cannot survive without the host.

Commensalism

• Commensalism occurs when one organism benefits and the other is unaffected; cattle egrets benefit from livestock stirring up insects.

Adaptations

• Structural adaptations are body parts that aid survival, like bat wings.
• Behavioral adaptations are habits or actions that aid in survival.
• Functional adaptations are the way an organism’s body works (e.g., dolphin's use of echolocation), not requiring thought.
• An example of functional adaptation is a heart beating faster during exercise to supply blood to muscles.

Ecosystems and Food

• Natural ecosystems are sustainable when they maintain suitable conditions through necessary substances, energy input, and a range of species.
• Food is vital as it contains matter and energy.
• Plants, moss, algae, and bacteria, are producers that create food.
• Herbivores eat producers (e.g., koalas, snails, sheep).
• Carnivores eat herbivores (e.g., fish, tigers).
• Scavengers eat carrion (e.g., crows, Tasmanian tigers).
• Detritivores consume detritus (e.g., crabs, worms).
• Decomposers break down dead organisms, which is vital to ecosystems.
• Parasites live and feed on other organisms.
• A food chain is a sequence of organisms feeding on each other.

Food Webs

• A food web is all connected food chains in a community.
• Producers that make food will pass it on to other organisms in the food chain.

Consumer Classification

• Organisms are grouped by food chain position (consumer order).
• Producers are at the first position
• Herbivores at the second position
• First-order consumers consume them
• Carnivores are at the third position
• Second-order consumers consume them

Trophic Levels

• Trophic levels are hierarchical levels in an ecosystem, defined by the nutritional role and energy source of organisms.
• Energy is needed for building and repairing cells, movement, warmth, and internal processes.
• Only 10% of energy transfers to the next level in a food chain, with the rest used or lost, resulting in rarely more than four steps in a food chain.

Pyramids

• Pyramids of biomass show organisms' total mass at each food chain stage.
• Pyramids of energy show the energy of food materials at each level.
• Ecologists use these to compare ecosystems and understand area productivity.
• Only about 10% of the energy transfers from one organism to the next

Biodiversity

• Biodiversity is the variety of species and their populations in an ecosystem.
• A large number of species with distinct differences helps contribute to a biodiverse ecosystem
• Coral reefs have one of the most biodiverse ecosystems on Earth.

Impacts

• Bushfires start naturally or by humans and can positively impact ecosystems by promoting seed germination and flowering.
• Eucalypts contain oils in their leaves that help them catch fire easily, while thick bark insulates living cells.
• Droughts reduce rainfall, changing ecosystems and increasing the death rate of plants and animals.
• The death of plants removes resources.
• Floods occur from heavy rains, causing rivers to overflow and animals/plants to possibly drown.
• Habitat destruction, introduced species, insecticides, chemical pollution, and overcropping are human impacts.
• Some pesticides accumulate in organisms and increase along the food chain, causing serious effects such as cancer.
• Chemical pollution causes damage in ecosystems.
• Micro and macro plastics are a significant problem, and carbon dioxide contributes to global warming.
• Oil spills devastate ecosystems.
• Monitoring the environment protects against dangerous chemicals.

Introduced Species

• Introduced plants and animals may become feral animals.
• Many feral species outcompete native species due to available resources.

Overcropping

• Overcropping is when more animals are killed than breeding cycles can replace, such as some whale populations.

Nervous System

• Nerve cells/neurons carry electrical messages (nerve impulses).

Neurons

• Neurons operate at a very high speed and only operate in one direction.
• Cell bodies contain the nucleus
• Dendrites receive messages
• Axons send nerve impulses in one direction away from the cell body.
• Axon terminals (knobs) pass messages to neurons.
• Motor neurons carry messages from the CNS to effectors.
• Sensory neurons carry messages from sense organs to the brain and spinal cord.
• Effectors are muscles or glands.

Nerve Impulses

• Nerve impulses reach knobs at the end of the axons.
• A neurotransmitter is then released into the synapse to carry the message to the next neuron’s dendrite, which then sends off the electrical signal.
• Neurons are bundled to form nerves covered by the myelin sheath to electrically insulate and increase nerve impulse speed.
• White matter contains neurons with myelin; grey matter contains mainly cell bodies in the central nervous system
• The central nervous system includes the brain and the brain stem.

Brain Parts

• The cerebrum controls and regulates functions in the body.
• The brain has approximately 100 billion neurons, and an average volume of 1200-1400mL.
• Higher intellectual functions, conscious thought, control voluntary movement, and receive sensory messages from the body.
• There are two types of hemispheres: left (language and logical thinking) and right (creative and emotional).
• Responsible for coordination and balance, the cerebellum is located at the base of the cerebrum.
• The medulla controls vital functions such as breathing, blood pressure, and heart rate and is located in the brain stem.
• The cranium and vertebrae protect the brain and spinal cord.
• Cerebrospinal fluid surrounds the brain/spinal cord, provides neurons with nutrients, and also acts as a shock absorber.

Somatic Nervous System

• Sensory organs are receptors that detect changes in the environment (stimuli).
• Examples of stimuli include temperature, light, touch, smell, and sound.
• Mechanoreceptors sense touch and stretch, photoreceptors sense light, thermoreceptors sense temperature, and chemoreceptors sense chemicals.

Senses

• The skin senses touch, pain, and temperature.
• The ear is responsible for balance and has fluid-filled semicircular canals.
• Light photoreceptors are found at the retina; optic nerves send messages.
• Rods and cones are photoreceptors: rods in the low light and cones in bright light.
• Taste receptor cells are chemoreceptors and signal taste.

Autonomic Nervous System

• The autonomic nervous system handles all activities that occur without intention.
• The Sympathetic and Parasympathetic nervous systems are opposites that complement each other.
• The sympathetic nervous system speeds up the body functions and prepares for emergencies.
• Diverts blood flow and stops peristalsis.
• The parasympathetic nervous system slows everything down and controls the heartbeat and pupil.
• The stimulus follows the Stimulus-Response Model; receptors stimulate sensory nerves, then the brain, then motor nerves, and then the effector

Reflexes

• Reflexes help to survive, animals depend on information about their surroundings to avoid danger
• Reflexes help with the defence, escape, feeding and reproductive system of the body
• A reflex action is a quick and automatic response.

Endocrine System Parts

• The entire endocrine glands make up the endocrine system
• The endocrine glands make hormones as necessary
• The hormones acts a messages
• These messages are coordinated by the pituitary gland which responds to information from the hypothalamus
• The hupothalamus links the nervous system and the endocrine system and helps in checking the internal environment in the body
• The hypothalamus will then screte hormones in a bid to act on the pituitary gland
• Controls body temperature and metabolism

Pitutitary Gland

• The pituitary gland can respond to the hypothalamus by either secreting further hormones
• It is also responsible in controlling the activities of the other endocrine glands

Hormones

• Hormones are produced in small amounts
• A few hormones which reach all body cells, travel via the bloodstream
• Response time varies
• May even take 48 hours for a response to occur

Homeostasis

• Homeostasis is the process which maintains the body
• In a bid to determine internal environmental factors they should control body temperature, glucose and salt

Sugar and Insulin

• Insulin causes the liver and muscles to take glucose to the blood
• Glycogen is then stored in the body

Glucose and Insulin

• Pancreas releases the hormone glucagon
• Glucagon can cause sugar and glycogen to be converted into glucose
• Glycogen is then released into the blood