Sci Chap 12 Flashcards
(35 cards)
Provide examples of ecosystems in SG.
East Coast Beach, Sungei Buloh mangrove
provide general ecosystems on Earth.
Tundra, grasslands, deserts, rainforests.
Explain the effect of climate change on ecosystems.
Climate change, which is caused by human activities, has disrupted the balance in some ecosystems. For instance, waters in tropical regions have become warmer due to climate change. This has caused tropical marine life to move to temperate regions which are cooler, and where they were originally not found. In these temperate regions, some of the tropical fish eat up kelp, threatening the survival of marine organisms living in habitats made up of kelp.
Describe the 5 factors affecting the environment.
A suitable combination of physical factors allows pants to grow and thus provide anims with food and shelter. Animals are then able to survive and reproduce.
air
Air contains the gases that organisms need to live. Plants need carbon dioxide for photosynthesis, and most organism need oxygen for respiration. Land organisms take in oxygen from the air, while most aquatic organisms take in oxygen dissolved in water. However, polluted water contains less dissolved oxygen than fresh, clean water. Thus, many fishes cannot survive in polluted water, but some organisms have adapted to survive in low-oxygen habitats.
water
All organisms need water to survive. It forms the main component of the cell protoplasm. The amount of water in any place depends on the rainfall it receives. In general, more organisms can be found where water is available.
light
Plants need light to make food through photosynthesis. Most plants are adapted to receive as much sunlight as possible. However, some plants such as mosses and ferns grow better in moist, shaded areas. The amount of light available determines the kinds of plants, and hence, the kinds of animals that are found in a habitat. It also afects the rate of photosynthesis and growth in plants. This, in turn, affects the rate of growth of animals, as animals depend directly or indirectly on plants for food.
temperature
Most plants and animals can survive in temperatures between 0°C to 45°C. Low temperatures slow down the rate of photosynthesis in plants stunt their growth, and allow down blood circulation in animals, making them sluggish. However, some organisms adapt to survive under more extreme conditions. Temperature affects the rate of enzyme reactions and therefore affects the metabolic rate and growth of organisms.
e.g. polar bears have a thick coat fur to trap body heat to stay warm.
acidity/alkalinity
Land plants and aquatic organisms are pH-sensitive. Most organisms cannot survive in extremely acidic or alkaline environments. Land plants cannot absorb mineral salts from the soil if it is too acidic. Freshwater organisms can tolerate a pH of about 7, while marine organisms can tolerate a pH of about 8. Carbon dioxide is slightly acidic. When aquatic plants photosynthesise during the day, dissolved carbon dioxide in water is used up, thus making it more alkaline.
Describe and compare the characteristics of the 2 different environments.
HOT DESERT
- Extreme temperatures
- Lack of water
- Few plants and animals can survive under the harsh physical conditions of deserts.
COLD DESERT
- Extreme cold
- A lot of water in the form of ice.
- Only plants that have shallow root systems and mature quickly can survive long periods of darkness during winter months. These plants grow in a thick layer of coi that is free from ice.
- Relatively few animals live in cold deserts.
Explain how organisms adapt to their environment.
Only organisms that are suited to live in their specific environment survive long enough to reproduce. They have adaptive traits that enable them to grow well in their environment. Adaptive traits can be structural and behavioural.
structural
Structural adaptations refer to the physical characteristics of an organism that help it to survive in its habitat.
Examples include scales on a crocodile to protect it from heat and injury, and the waxy leaves of wax plants that help it to reduce water loss.
behavioural
Behavioural adaptations refer to the different behaviours of an organism that allow it to survive in its habitat.
Examples include:
- Sand bubbler crabs burrow into sand to escape from heat and predators.
- Some trees shed leaves during autumn to prevent water loss u the winter.
- Bears hibernate to survive the winter.
Explain how the environment shapes the organisms’ adaptations.
The physical factors of an environment shape the adaptative traits of plants and animals that live in it. Some organisms are unable to survive changes to the environment and die, while organisms that survive will go on to reproduce. These offspring will have the same adaptative traits as their parents and can survive in the new environments.
Describe the adaptations in the rainforest environment.
The physical factors of the rainforest include:
- Humid and warm air
- Frequent and abundant rainfall
- High average temperatures
- Narrow temperature range
- Large amount of sunlight that reaches the tree canopy, but little sunlight that reaches the ground.
organisms with adaptations to the rainforest include:
- Velvet tamarind trees, which have large, wide, buttress roots, which provide support and help to take in minerals near the surface of the soil. It also grows very tall to allow leaves to trap more sunlight (structural)
- Banded leaf monkeys, that have strong arms that allow them to swing from tree to tree. (structural). They also stay in groups for protection from predators and fight other groups to compete for food in their territory (behavioural).
Describe the adaptations in the mangrove swamp environment.
The physical factors of the mangrove swamp include:
- Located on the coast
- Immersed in seawater at high tide
- Becomes dry at low tide
- Exposed to freshwater when it rains
- Exposed to a lot of sunlight.
Organisms with adaptations to the mangrove swamp include:
- Mangrove trees, that have many strong, breathing roots to anchor them in the mud and obtain oxygen. They also have the ability to remove salt taken in from seawater, which allows their survival (structural adaptations)
- Pistol shrimps, with enlarged claws to enable them to shoot a jet of water and create a bubble. When the bubble bursts, the high pressure and temperature generated catch their prey off guard (structural). They live in burrows to avoid predators (behavioural).
What is an ecosystem?
An organism is usually adapted to the environment it lives in. Organisms of the same kind living in the same environment form a population. Different populations of plants and animals living and interacting in a particular environment make up a community. The interactions between a community and its physical environment make up an ecosystem.
Define predators and prey and their relationship.
Predators hunt and kill other animals for food. Adaptations include sharp teeth, high speed, and sharp senses for detecting prey.
A prey is killed and eaten by another animal. Adaptations that prevent prey from getting caught include: small size, high speed, and mimicking unpleasant objects.
Define Mutualism.
The relationship in which 2 or more organisms support or benefit one another is called mutualism.
One way in which mutualism can occur is when one organism provides another with protection in exchange for food.
For example, butterflies feed on nectar from flowers; in exchange, the butterflies help pollinate the flowers.
Define parasitism.
Parasitism is a relationship between 2 organisms in which 1 (the parasite) benefits at the expense of the other (the host).
The parasite is the organism that causes harm to another organism, which is known as the host, without killing it. The parasite benefits by obtaining its food or nutrients from the body of its host, which can be a plant or an animal.
e.g. the rafflesia plant gets all its nutrients at the expense of certain surrounding vines as it has no stem, leaves, roots or chloroplasts.
Define commensalism.
An association between 2 organisms in which 1 benefits and the other derives neither benefit nor harm. e.g. Sparrows benefit by setting up homes underneath fierce osprey for protection.
What is the ultimate source of energy?
The Sun
Define producer, primary/secondary/tertiary consumer.
producer (alw green plants) -> primary consumer -> secondary consumer -> tertiary consumer.
Explain the flow of nutrients in an ecosystem.
When producers are eaten by consumers, nutrients from them are transferred to the consumers. When they are eaten by their predators, the nutrients in them are passed on to their predators. Decomposers break down the faces of organisms and remains of dead organisms, and return the nutrients in them to the environment. Hence, the flow of nutrients in an ecosystem is cyclical.
Define decomposers.
Decomposers break down the complex nutrients in faeces and dead bodies of plants and animals. In the decomposition process, carbon dioxide is released, which escapes into the atmosphere, soluble mineral salts are released, which dissolve in the soil water, and water is released.
Define scavengers.
Scavengers break down dead & decayed matter into smaller pieces. They are not decomposers.
Define the carbon cycle.
The carbon cycle provides a continuous supply of carbon dioxide for photosynthesis and enables energy to flow through the ecosystem.
How can the balance of an ecosystem be upset in the following ways?
Intro of new animals and plants into the habitat. Disease outbreaks, which can kill one kind of animal or plant. Human activities such as deforestation and over-fishing.
Name one cause, effect and conservation effort of water pollution.
Cause: discharge of chemical wastes from factories.
Effect: contamination of groundwater.
Conservation efforts: River clean-up projects.
Name one cause, effect and conservation effort of air pollution.
cause: clearing of forests by burning
effect: global warming, haze
Conservation effort: turning to alternative forms of renewable energy, such as using wind turbines.
Name one cause, effect and conservation effort of land damage.
Cause: Land overuse.
Effect: Formation of deserts and unproductive land.
Conservation tactic: Gov. designating land as forest reserves, prohibition of tree felling and hunting.
