life science review of grade 6 science. classification of organisms taxonomy – the science of...
TRANSCRIPT
Life Science
Review of Grade 6 Science
Classification of Organisms
Taxonomy – the science of describing, classifying, and naming living things
Carolus Linnaeus – the Swedish scientist who founded modern taxonomy
Classification System Kingdom (most general way to group organisms) Phylum Class Order Family Genus Species (most specific way to group
organisms)
The Five-Kingdom Classification System –
Monera Protista Fungi Plantae Animalia
Monera – Eubacteria (modern bacteria) & Archaebacteria (ancient bacteria)
include bacteria and blue-green algae have no nuclei oldest & most numerous organisms on
Earth
Protista
include amoebas and euglenas single cells and microscopic have nuclei but lack any specialized
tissues and organs commonly called protozoa
Fungi
includes mushrooms, yeasts, and molds yeasts are unicellular, but the rest are
multicellular decompose other organisms and are
important to maintain a healthy ecosystem
Plantae
includes mosses, ferns, flowers, and trees (multicellular organisms)
most red, brown, and green algae (single-celled organisms)
can make their own food by photosynthesis
cannot move about freely
Animalia
includes sponges, jellyfish, worms, shellfish, starfish, insects, fish, amphibians, reptiles, birds, mammals, and humans
multicellular organisms get energy by eating other organisms are able to move about freely
Key words –
invertebrate – animal without a backbone vertebrate – animal with a backbone
Structure and Function of Cells
All organisms are made up of cells. Cells are the building blocks of life.
Key words – unicellular – just one cell multicellular – many cells organelles – tiny structures in cells
Cell Organelles and their Functions
cell membrane plant & animal a semi permeable membrane that controls movement of molecules into and out of the cell
nucleus plant & animal the control center of the cell; contains chromosomes that carry the genes
nuclear
membrane
plant & animal a semi permeable membrane; encloses and protects the nucleus
vacuoles plant & animal storage sac that contains fluids, pigments, and other substances
mitochondria plant & animal the powerhouse of the cell; releases energy to support all cell activities
endoplasmic
reticulum
plant & animal system of tubules inside the cytoplasm for transport of materials
cytoplasm plant & animal clear, thick fluid that holds all the organelles in a cell
ribosomes plant & animal contain enzymes that help make proteins
chloroplasts plant contain chlorophyll; where photosynthesis happens
cell wall plant the outer non-living cellulose structure that helps the cell keep its shape
Key Terms –
Mitosis – the process of one cell dividing into two equal and identical cells; makes body cells
Meiosis – the process of one cell divides two times to make sex cells with half the number of chromosomes of a body cell
Photosynthesis
the process that plants use to capture energy from the sun and change it into food
happens in the chloroplast chlorophyll, a green pigment in leaves, converts
sunlight into food carbon dioxide, water, and sunlight energy is
turned into sugar or food (glucose) and oxygen
Cellular respiration
the process used by complex organisms, such as humans, to get energy from food
happens in the mitochondrion food-sugar (glucose), oxygen is turned into
carbon dioxide, water, and energy (ATP)
Reproduction and Heredity
Reproduction – involves creating an entire organism
Two Methods of Reproduction –
Asexual reproduction
Sexual reproduction
Asexual reproduction –
the offspring (young) has only one parent the offspring are clones of their single
parent by mitosis (exact copies of the original cell)
algae, bacteria, strawberries (runners), tubers (white potatoes), bulbs (tulips, onions), regeneration (planaria, starfish)
Sexual reproduction –
the offspring has two parents the offspring form when a sperm and an egg
join by a process called fertilization offspring have some of the traits of both
parents and other traits not visible in the parents but nonetheless present offspring
the offspring have genetic material from both parents
The nucleus -
contains the organism’s genetic material contains 46 chromosomes (threadlike
strands of DNA that carry the code or genes telling the traits the organisms will have)
Gametes –
are the sex cells (eggs and sperm) contain 23 chromosome (half the number
of chromosomes found in a body cell) made in the reproductive organs made by a process called meiosis (the
number of chromosomes in the gamete is reduced by half)
Key Terms –
dominant trait – the trait that appears in an offspring when two different genes are mixed
recessive trait – the trait that does not appear when two different genes are mixed; for a recessive trait to be seen, two recessive genes must be present
zygote – is the single cell formed when the egg and sperm unite; a fertilized egg
embryo – is the name of the fertilized egg once it begins dividing by mitosis
variation – differences in traits among individuals of a species
Systems of Living Things
organized differentiated
Organization of Living Things
cells tissues organs
organ system organism
Organ Systems and their FunctionsCirculatory the blood carries food, oxygen, and nutrients to all areas of
the body
Digestive breaks down food and absorbs nutrients
Endocrine uses chemical hormones to control other body systems
Excretory gathers the wastes from the digestive, respiratory, and circulatory systems and discharges them from the body
Immune protects us from disease - using the skin as a barrier to the outside world and using white blood cells and antibodies
Muscular allows body movement, maintains posture, moves food
Nervous controls and coordinates; carries nerve messages to and from the brain and spinal cord and rest of the body
Reproductive takes its signals from certain hormones to make sex cells to allow offspring to be produced
Respiratory brings oxygen in and removes carbon dioxide from body
Skeletal Protects, supports, allows movement, makes blood cells, and stores minerals
Evolution and Biodiversity
evolution – the process in which inherited characteristics within a population change over generations such that new species sometimes arise
heredity – your characteristics that make up your physical body are handed down to your through the genetic material from your ancestors
variation – differences in traits among individuals of a species
adaptations – a characteristic or trait that improves an individual’s ability to survive and reproduce
natural selection or survival of the fittest – the most fit organisms will survive and reproduce and pass their good traits to their offspring
Organisms and the Environment ecology – the study of the relationship of living things to
the environment
ecosystem – the living community of organisms and their nonliving environment
food chain – a way of showing the order in which food energy passes from one organism to another
food web – two or more food chains
niche – the job or role an organism plays
competition – when organisms struggle with one another to get the things they need to survive
Key Terms prey – the animal that is eaten predator – an animal that eats other animals parasite – an organism that lives off another
organism host – the organism that provides a home for
another organism socialization – when a species live together in
groups to care and protect their young; primates, whales
cooperation – when organisms work together; wolves, lions, whales
Symbiosis
organisms from different species work together in groups and form partnerships that help the organisms involved
Three types of Symbiosis:
mutualism – a form of symbiosis in which both organisms benefit
commensalism – a form of symbiosis in which one organism benefits and the other is not harmed
parasitism – a form of symbiosis in which one organism benefits and the other is harmed
Food Levels Producers
Consumers Decomposers
These food levels are used to show how far an organism is from the primary source of all food energy, the Sun. The closer an organism’s food source is to the Sun, the more numerous the organism.
Producers
make their own food all green plants, phytoplankton
(microorganisms in the ocean), algae
Consumers – eat other organisms primary consumers (herbivores) - eat only
plants or parts of plants
secondary consumers (carnivores) – eat herbivores or other carnivores
omnivores – (primary & secondary consumers) - eat both plant & animals
Decomposers
break down dead organisms recycle nutrients bacteria, earthworms, and fungi
Changes in Ecosystems over Time abiotic – nonliving factors in the environment
biotic factors – living factors in the environment
biome – a large area of land that has the same climate
biodiversity – the variety in the types of organisms that live in an area
catastrophic disturbance – unexpected events such as volcanic eruption, forest fires
Key Terms eutrophication – when extra nutrients get into a
river, lake, or bay, they cause unusual algae growth. When too many aquatic organisms, such as algae, grow in a body of water, they deplete the level of oxygen in the water so that other organisms cannot live
phototropism – the tendency of plants to bend or lean toward light in order to get the most energy from photosynthesis
succession – a series of changes in a living community
climax community – a stable community at the end of succession