BIOLOGY
EOC TEST REVIEW II
LINNAEAN SYSTEM
In the mid-1700’s, Carolus Linnaeus developed a new classification system that revolutionized taxonomy. He suggested that organisms be classified with other organisms that had similar structures. Organisms are known by their common name, such as red maple. Organisms have been given a scientific name, the genus followed by the species. The genus and species for the red maple tree is Acer rubrum. The genus begins with a capital letter and the second name is always lower case. All scientific names are written in Latin, and are italicized or underlined.
A classification key can be used as an aid to identify organism. It uses an organisms general characteristics and special features to find its appropriate placement.
TAXONOMY
Scientists these days study chromosome structure, reproductive potential, biochemical similarities, and embryology to determine the relationships among organisms. The classification levels are:
Kingdom-Phylum-Class-Order-Family-Genus-Species
(King Philip Came Over For Great Spaghetti)
KINGDOMS
MONERA
Examples: Bacteria
Characteristics: prokaryote, microscopic, lives as a single cell
Reproduction: binary fission (splits in two)
Beneficial: decomposers of matter, in digestive system, nitrogen-fixers
Harmful: can cause diseases like strep throat, pneumonia
PROTISTA
Examples: Most unicellular organisms - protozoa, amoeba, zooplankton, euglena, paramecium, and algae
Characteristics: eukaryotes, mainly microscopic, single celled or multicellular; some are autotrophic (algae) and many are heterotrophic (protozoans)
Reproduction: asexual or sexual
Beneficial: some are harmless
Harmful: sleeping sickness, malaria
FUNGI
Examples: mushrooms, bread molds, slime molds, rusts and smuts, yeast
Characteristics: eukaryotes, mainly multicellular, parasitic, symbiotic, heterotrophic,
Reproduction: asexual, sexual
Beneficial: yeast, penicillin, decompose organic material
Harmful: cereal rusts, ringworm, athlete’s foot,
PLANTS
Examples: All multicellular plants - Mosses, liverworts, hornworts, ferns, gymnosperms (pine cone plants), angiosperms (flower-bearing plants)
Characteristics: eukaryotes, multicellular, can’t move, autotrophic
Growth: based on hormone action
Reproduction: asexual, sexual by spores, seeds, flowers, and cones
ANIMALS
Examples: All multicellular animals - Invertebrates and vertebrates (fish; amphibians – frogs, salamanders; reptiles – snakes, lizards, turtles; birds; and mammals)
Characteristics: eukaryotes, multicellular, heterotrophic,
Growth: based on hormone action and nutrition
Reproduction: asexual, sexual
PLANTS
One of the major ways that land plants differ is the way they transport water and nutrients throughout the plant body. The majority of land plants have an internal system of connected tubes and vessels called vascular tissues. These plants, called vascular plants, are the plants that you are the most familiar with –maple trees, grasses, roses, and house plants. Vascular plants have roots, stems, and leaves.
The other group of plants is called bryophytes. They lack vascular tissue. They transport water and nutrients by osmosis and diffusion.
NONVASCULAR PLANTS
Bryophytes need a lot of water to survive. Remember that they transport materials by osmosis and diffusion. This requires a lot of water. Almost all bryophytes are small plants and they grow close to the ground. Gravity can restrict the processes of osmosis and diffusion.
VASCULAR PLANTS
Plants with vascular tissue are called tracheophytes. They have true roots, stems, and leaves. They have an internal network of tubes that carry water, nutrients and glucose made from photosynthesis throughout the plant.
The roots absorb water and nutrients from the soil and they anchor the plant. The roots also store food that was made in the leaves. The stem contains vascular tissue that transports substances between the roots and the leaves. The stem also supports plant growth above the ground. It is the backbone of the plant. There are two types of vascular tissue: xylem and phloem. Xylem transports water and minerals absorbed by the roots up to those parts of the plant that are above the ground. The phloem carries sugar and other soluble organic materials produced by photosynthesis from the leaves to the rest of the plant.
The leaves use sunlight, water, and carbon dioxide to carry out photosynthesis. They also transport the food they produce to the rest of the plant in a process called translocation. In addition leaves exchange gases and water vapor with the atmosphere. The outside of the leave is covered with a waxy layer that slows the evaporation of water from the leaf. The waxy layer covers the epidermis, a single transparent layer of cells. The epidermis has openings called stomata. Each stomata has a guard cell on each side. The guard cells change shape to control the exit and entry of water and gases. Most guard cells are located on the underside of the leaf where the surface is shaded. Ninety percent of the water that enters the roots is lost through the leaves in a process called transpiration.
The middle portion of the cell is called mesophyll. The cells of the mesophyll contain the chlorophyll and other pigments. Vascular bundles extend into the tissue of the mesophyll. They are seen in the leaves as veins.
GYMNOSPERMS
Gymnosperms are one of two groups of vascular plants. Gymnosperms produce their seeds in cones and generally keep their leaves throughout the year (evergreen).
ANGIOSPERMS
Angiosperms are flowering plants. They produce seeds enclosed in fruits. (Gymnosperm seeds are uncovered in their cones.) Angiosperms are deciduous plants. That means that they lose their leaves every fall. Angiosperms produce seeds with a cotyledon (seed leaf) inside. A cotyledon provides food for the plant embryo in the seed when it begins to grow.
REPRODUCTION
Reproduction in angiosperms is different. All angiosperms produce flowers. Some flowers have both male and female parts and some have just one sex. The flower attracts insects for pollination and thus fertilization to make a seed. After fertilization, the flower petals die and the remaining flower structures form a fruit. The fruit protects the seed and helps to disperse them in various ways. Then, an animal eats the fruit and leaves the seed in its feces elsewhere.
SEXUAL REPRODUCTION
In plants that produce them, the flower functions in sexual reproduction. Flowers consist of modified leaves. The essential flower parts are the ones that produce gametes and carry out sexual reproduction. These include male parts called stamens and female parts call pistils.
Most flowers have three, four, or five stamens. The thin stem-like portion of a stamen is called the filament. Pollen is produced at the tip of the filament, generally in an oblong structure called the anther. Most flowers have a single pistil. The pistil contains three parts. The swollen base of the pistil is called the ovary. Within the ovary, one or more ovules produce the egg cells. The slender middle part of the pistil is called the style. At the tip of the style is the stigma. The stigma produces a sticky substance to which pollen grains become attached.
Animals, wind, and water all transport pollen from flower to flower. The nonessential flower parts are modified to aid the specific type of pollination a plant undergoes. In flowers that are pollinated by animals, the stem and receptacle hold the flower out where its colors and scent are most obvious. Some flowers produce nectar, a sweet liquid.
Fruits are formed when the egg is fertilized and the ovary begins to swell and ripen. It changes color and becomes fleshy or dry. Animals eat the fruit and pass the seed out to new places through their waste.
ASEXUAL REPRODUCTION
Many plants can produce new plants without the aid of fertilization.. Asexual reproduction is common in strawberries, potatoes, irises, spider plants, and grasses. Remember that any plant produced asexually has the same genes as its parent plant.
Asexual reproduction can be accomplished naturally through vegetative propagation. This means that the plant sends out runners or long modified stems (rhizomes) and grows new plants from these parts.
ECOLOGY
ECOSYSTEMS
Life on earth extends from the ocean depths to a few kilometers above the earth’s surface. The area where life exists is called the biosphere. The biosphere can be more easily understood by breaking it into smaller components called ecosystems.
An ecosystem is a physically distinct, self-supporting unit of interacting organisms and their surrounding environment. It is made up of biotic and abiotic interactions. The biotic factors of an ecosystem are the living organisms in the area. The abiotic factors are the non-living, or physical, components of the area like light, soil, water, temperature, wind, and nutrients. The essential factors that make an ecosystem successful are a source of energy, a storage of water, and the ability to recycle water, oxygen, carbon, and nitrogen.
Ecosystems must maintain an ecological balance. This can be helpful or harmful to the members that make up the community depending upon whether they are predators or prey. A predator is an animal that feeds on other living things. The animal it feeds upon is the prey. Lions (predator) hunt down and kill antelope (prey).
Each of the biotic organisms in an ecosystem interrelate with the others. A symbiotic relationship between two members of a community is one in which one or both parties benefit. Commensalism is a relationship in which one member is the host, but causes no harm to the other organism (barnacles on whales). Mutualism is a relationship in which two living organisms live together in dependency on each other (the protozoa in the human intestine). Parasitism is a relationship that involves a host organism which is harmed by the presence of the other organism (fleas on dogs and cats).
COMMUNITIES
An ecosystem’s biotic factors interact with each other and compose a community of living things that coexist. Each community is composed of populations. A population is a group of small individuals of a single species that occupy a common area and share common resources. The number of populations within a community varies. A tropical rain forest community may have thousands of populations while a desert community may have very few.
Just like communities are made up of populations, each populations is composed of interacting individuals. Each individual organism lives in a specific environment and pursues a particular way of life. The surroundings in which a particular species can be found is called its habitat. An organism can inhabit an entire ecosystem like a woodpecker might occupy the whole oak forest. But the spider may only inhabit the trunk of one of the oak trees.
The way of life that a species pursues within its habitat is called its ecological niche. An organism’s niche is composed of biotic and abiotic factors. Some niches can be very broad (rats) while others can be very limited (panda).
THE FLOW OF MATERIALS
Each ecosystem has its producers, consumers, and decomposers. They make up a cycle called a food chain. Food passes from one organism to another in the food chain. Energy is used up by each consumer in the food chain. Plants make food, animals eat plants, some animals eat other animals, and some animals eat plants and other animals. Herbivores are animals that eat only plants. Carnivores are animals that each only other animals. Omnivores are animals that eat both plants and animals. A Saprophyte is an organisms that feeds on dead organisms.
There are many food chains in an ecosystem. The least amount of energy consumed is the item highest in the food chain. In the preceding example that would be the human. All the food chains in an ecosystem make up the food web of the area. Most food chains overlap because many organism can eat more than one type of food.
All organisms need certain chemicals in order to live. The most important ones are water, oxygen, carbon, and nitrogen. The continuous movement of chemicals throughout an ecosystem is called recycling.
ECOLOGICAL SUCCESSION
An ecosystem goes through a series of changes known as ecological succession. Succession occurs when one community slowly replaces another as the environment changes. As succession in a community continues, it finally reaches a climax community. A few organisms establish themselves and become the dominant species in the area. The complete process of succession may take anywhere from a hundred to thousands of years, depending upon the communities.
POPULATIONS IN ECOSYSTEMS
The population of an area is affected by the new offspring produced in the area. New plants and animals moving in from other places increase the size of the population. The death of organisms and animals moving out of the area decrease the size of the population. There is a direct relationship between the number of plants and animals in an area which is in ecological balance. If the number of one of them is increased or decreased, it will affect the numbers of the other. During deer season, the number of deer is reduced by man. The plants that the deer eats will increase during this season.
A change in populations may be helpful or harmful to the community. If insects are killed by insecticide, the animals that depend on they for food must move elsewhere. Even the human population changes as he seasons change. In the summertime, the coastal area is more widely populated by vacationing people. In the wintertime, the snowy, mountainous areas are more populated by snow skiers.
BIOMES
Communities are members of a larger ecological unit called a biome. A biome is an extensive area of similar climate and vegetation. A biome’s abiotic (non-living) factors determine what plants and animals live there. The major influences are temperature, light intensity, and patterns of rainfall, which determine the availability of water. There are six basic biomes on earth: tundra, taiga, grassland, deciduous forest, desert, tropical rain forest.
Biomes that are closest to the poles experience the coldest weather conditions for they are furthest away from the sun due to the tilting of the earth.
ECOLOGICAL PROBLEMS
Natural resources are necessary for human survival and the making of necessary products. The natural resources are water, air, soil, wildlife, and forests. Problems that are now being faced are related to erosion, soil depletion, species extinction, deforestation, desertification, and water shortages. Efforts to reverse these problems and their environmental damages are found in the planned programs of reforestation, captive breeding, and planned farming through efficient plowing and planting procedures.
Disruptive changes can easily upset the stability of an ecosystem. Destructive acts of nature can occur. A forest fire can destroy all plant and animal life in a forest, along a river, and around the shore of a pond. It can also pollute a pond with ash.