8th Grade Science

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Table of Contents:Organisms and Environments

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Organisms and Environments Vocabulary Pages 3-7

Organism Relationships Page 8

Environmental Changes Page 9

Biotic and Abiotic Factors Page 10

Biodiversity Page 11

Ecological Succession Page 12

Human Dependence on Ocean Systems Page 13

Dichotomous Keys Page 14

Natural Selection Page 15

Sexual vs. Asexual Reproduction Page 16

Plant Cells Page 17

Animal Cells Page 18

Inherited and Acquired Traits Page 19

Levels of Organization Page 20

Characteristics of Organisms Page 21

Body Systems Page 22

Organisms and Environments Assessment Pages 23-24

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Organisms and Environments VocabularyOrganism Relationships

Producer - an organism that can make its own food through photosynthesis

Consumer - an organism that gains energy by feeding on other organisms

Decomposer - an organism that breaks down waste and dead organisms

Scavenger - an animal that feeds on the bodies of dead organisms

Herbivore - a consumer that feeds on plants only

Carnivore - a consumer that feeds on animals only

Omnivore - a consumer that feeds on plants and animals

Predator - an organism that hunts other organisms for food

Prey - an organism that is hunted and eaten by another organism

Parasite – an organism that lives in or on another organism and causes harm to it

Host – an organism that a parasite lives in or on

Environmental Changes

Short Term Environmental Changes - changes that occur quickly in an ecosystem and affect organisms immediately

Long Term Environmental Changes - changes that occur slowly over time and affects organisms over several generations

Drought - a severe lack of rainfall in an area over a certain time period

Flood - days of heavy rainfall that cause rivers to rise over their banks

Hurricane - an intense storm that forms in the ocean with swirling winds up to 150 miles per hour

Tornado - a spinning column of air with wind speeds up to 300 miles per hour

Wild fires – a large, destructive fire that spreads quickly over woodland or brush

Climate Fluctuation – a change in global or regional climate patterns

Deforestation – the result of cutting down or clearing all the trees in an area

Pollution – the contamination of air, water, or soil by substances that are harmful to living organisms

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Organisms and Environments VocabularyBiotic and Abiotic Factors

Biotic Factor - a living or once living part of an ecosystem

Abiotic Factor - a nonliving part of an ecosystem

Biodiversity

Genetic Biodiversity - the total number of genetic characteristics in the genetic makeup of a species

Ecological Biodiversity - the variety of all living organisms in an ecosystem

Species - a distinct group of animals or plants that have common characteristics and can breed with each other

Population - all of the members of one species in a particular area

Community - all of the different populations that live together in an area

Habitat - the place an organism lives that provides all of its needs

Ecological Succession

Primary Succession - changes that occur in an area where no ecosystem previously existed

Secondary Succession - changes that occur in an area after a disturbance in an existing ecosystem

Pioneer Species - the first species to occupy a new ecosystem or habitat

Climax Community – a community in which populations of plants or animals remain stable and exist in balance with each other and their environment

Human Dependence on Ocean Systems

Overfishing - fish and shellfish populations dropping quickly because they are being removed from oceans faster than they are able to reproduce

Habitat Destruction - the process by which a habitat is damaged or destroyed to such an extent that it no longer is capable of supporting the organisms that live there

Artificial Reefs - a human-made underwater structure built to promote marine life

Dichotomous Keys

Dichotomous Key - a tool that allows the user to determine the identity of organisms

Classification - the process of grouping something according to its qualities or characteristics

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Organisms and Environments VocabularyTaxonomy - the classification and naming of organisms in an ordered system

Binomial Nomenclature - the scientific system of giving a genus and species name to each plant and animal

Natural Selection

Natural Selection - organisms that are better suited for their environment are more likely to survive and reproduce

Charles Darwin - The naturalist known for his contributions to the theory of evolution by natural selection

Adaptation - a characteristic that helps an organism survive in its environment and reproduce

Selective Breeding - the intentional breeding of two individuals to produce offspring with favorable characteristics

Sexual vs. Asexual Reproduction

Sexual Reproduction - the production of a new living organism by two parents

Asexual Reproduction - a type of reproduction by which offspring arise from a single organism

Offspring - the organism or organisms resulting from sexual or asexual reproduction

Gamete - the male or female reproductive cell that contains half the genetic material of the organism

Genetic Variation - genetic differences between individuals or populations

Binary Fission - a cell dividing into two cells after duplicating its genetic material

Budding - an organism forming a growth that develops into a genetically identical organism and then breaks off

Fragmentation - an organism splits into pieces and each piece develops into a genetically identical organism

Plant and Animal Cells

Structure - how the cell is built

Function - the specific job or role of an organelle

Nucleus - controls the activities of the cell

Cell Wall - rigid layer surrounding a plant cell that provides support, strength, and shape (plant cell only)

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Organisms and Environments VocabularyCell Membrane - controls what comes in and out of the cell

Cytoplasm - thick gel-like fluid inside the cell between the nucleus and the cell membrane

Mitochondria - produces the energy needed for the cell to carry out its functions

Golgi Bodies - packages and distributes materials to other parts of the cell

Endoplasmic Reticulum - passageways in the cell that carry materials from one part of the cell to another

Vacuole - the storage area of the cell

Chloroplast - contains chlorophyll and makes food from sunlight (plant cell only)

Inherited and Acquired Traits

Inherited Trait - a trait that an organism is born with that is obtained from parents or ancestors

Acquired Trait - a trait that an organism obtains during its lifetime through its environment

Gregor Mendel - Austrian monk who discovered the basic principles of heredity; known as the “Father of Genetics”

Genetics - the scientific study of heredity

Heredity - the process in which characteristics are passed from parents to offspring

Gene - a segment of DNA that has the code for a specific trait

Chromosome - the location where genetic information is stored within the nucleus of a cell

DNA - long chains of molecules that make up chromosomes

Levels of Organization

Cell - the basic unit of life

Tissue - a group of similar cells that do the same sort of work

Organ - a group of tissues that work together to perform a specific function

Organ System - a group of organs that work together to perform a specific function

Organism - a living individual that can reproduce, grow, and maintain homeostasis

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Organisms and Environments VocabularyCharacteristics of Organisms

Prokaryote - an organism whose cells lack a nucleus and other organelles

Eukaryote - an organism whose cells contain a nucleus and other organelles

Unicellular - an organism that is made up of only one cell

Multicellular - an organism that is made up of many cells

Autotroph - an organism that is able to produce its own food through the process of photosynthesis

Heterotroph - an organism that must consume other organisms in order to obtain energy

Body Systems

Circulatory - transports oxygen and nutrients to the body and removes CO2 and other waste products

Respiratory - supplies the blood with oxygen in order for the blood to deliver oxygen to all parts of the body

Skeletal - provides support, movement, protection, blood cell production, and calcium storage

Muscular - responsible for the movement of the human body

Digestive - breaks down food into tiny molecules to allow the body to absorb nutrients

Excretory - removes wastes that can cause toxic build up and lead to diseases or death

Reproductive - produces eggs or sperm and nourishes offspring until birth

Integumentary - acts as a barrier to protect the body from the outside world

Nervous - controls and transmits signals between different parts of the body

Endocrine - glands that secrete hormones to regulate metabolism, growth, sleep, and reproduction

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Organism Relationships

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Producers• Obtain energy from the Sun through the process of photosynthesis• Eaten by herbivores and omnivores• Examples: green plants, algae, and phytoplankton

Consumers• Obtain energy by eating other organisms• Can be classified as herbivores, carnivores, or omnivores• Examples: humans, sharks, and bears

Predator• Hunts and kills other animals for food• Examples: lion hunting a gazelle, seal hunting fish, frog hunting insects

Prey• Animals that are hunted and killed for food• Examples: mice hunted by an owl, worm hunted by a bird, rabbit hunted by a fox

Parasite• Organisms that live in or on another organism and cause harm to it• Examples: fleas, ticks, and lice

GrassMouse

Rabbit Flea

Snake Hawk

Host• Organism that a parasite live in or on• Examples: dogs, deer, and humans

Use the food web above to fill in an example of each of the following.

Producer - Consumer - Predator -

Prey - Parasite - Host -

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Environmental Changes

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Short Term Environmental Changes• Changes that occur quickly in an ecosystem and affect organisms immediately• Does not give organisms time to adapt to changes • Forces populations to move or possibly become extinct

Drought Flood Fire

Examples of Short Term Environmental Changes

Long Term Environmental Changes• Changes that occur slowly over time and affects organisms over several generations• Gradual changes that allow organisms time to adapt • Organisms become better adapted to survive in their environment

Climate Fluctuations Deforestation Pollution

Examples of Long Term Environmental Changes

List several short and long term environmental changes that affect organisms where you live.

Short Term Long Term

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Biotic and Abiotic Factors

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Biotic Factors• Living or once living part of an ecosystem• Can be producers, consumers, or decomposers• Examples: grass, ants, birds, mushrooms

Abiotic Factors• Non-living part of an ecosystem• Come in different types and vary among ecosystems• Directly affect how organisms survive• Examples: sunlight, temperature, altitude, rain

Biotic Factors

Tree Frog Fungi

Abiotic Factors

Humidity Clouds Pollution

Biotic Factors Abiotic Factors

Study the picture of a marine ecosystem below. List the biotic and abiotic factors.

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Biodiversity

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Biodiversity• Bio = life• Diversity = different or variation• Genetic biodiversity – variation in genes within a species• Ecological biodiversity – diversity of ecosystems, communities, and habitats• A variety of species with genetic variations allows an ecosystem the ability to maintain a healthy

environment

Biodiversity Facts• Scientists have identified 1.7 million species on Earth• Some researchers have estimated that there could be between 3-30 million species on Earth• Over half of all the species identified are invertebrates (organisms without backbones)

Importance of Biodiversity• Allows ecosystems to adjust to disturbances such as a wildfire, flood, or drought• Provides a variety of food sources for organisms• Genetic biodiversity helps species adjust to changes in their environment

Threats to Biodiversity• Habitat loss• Overfishing, overhunting, illegal poaching of endangered or protected species• Spread of disease• Invasive species• Climate fluctuations• Pollution

Low DiversityAverage DiversityHigh Diversity

Producers

Herbivores

Carnivores

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Ecological Succession

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Ecological Succession• A series of predictable changes that occur in a community over time• Can take place in a relatively short time period or an extremely long time period• 2 types of succession – primary and secondary

Stages of Primary Succession

Primary Succession• A series of community changes over a long period of time• New ecosystem formed where nothing previously existed (no soil, plants, or animals)• Process can take thousands of years • Example: an island formed from a volcanic eruption under the ocean’s surface

Bare RockMosses and Lichens break down rock to

form soilGrasses Small Shrubs Young Forest

Mature Forest –Climax

Community

Hundreds or Thousands of Years

Secondary Succession• A series of community changes over a relatively shorter period of time• Formation and regrowth of an ecosystem after a disturbance• Process can take hundreds of years• Example: the regrowth of a forest after a fire destroys it

Stages of Secondary Succession

Forest FireSoil already

present after fire

Grasses Small Shrubs Young ForestMature Forest –

Climax Community

Decades or Hundreds of Years

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Human Dependence on Ocean Systems

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Human Dependence on Ocean SystemsHumans depend on ocean systems for the following:1. Food – oceans provide fish and shellfish to large populations2. Water – oceans indirectly provide terrestrial (land) life with fresh water through the water cycle3. Transportation – oceans provide an efficient way to transport goods on ships4. Climate Regulation – ocean currents circulate warmer water from the equator to arctic regions and

cooler water from arctic regions to the equator; currents help to moderate temperature extremes5. Recreation – boating, fishing, diving, and surfing

Negative Human Impact on Ocean SystemsHumans negatively impact ocean systems in the following ways:1. Overfishing – populations of fish and shellfish are dropping quickly because they are being removed

from oceans faster than they are able to reproduce2. Runoff and Pollution – toxic chemicals from factories run off into rivers and end up in the ocean;

these toxic chemicals can kill fish or make them potentially dangerous for human consumption; fertilizers and pesticides wash off into rivers and are carried into the ocean

3. Habitat Destruction – many wetlands and other habitats have been destroyed by human developments and pollution

Positive Human Impact on Ocean SystemsHumans positively impact ocean systems in the following way:1. Artificial Reefs – humans create artificial reefs by sinking old ships, train cars, and other non-toxic

structures; these artificial reefs help to support large fish populations and new food webs; artificial reefs support life much like naturally occurring coral reefs

Negative Human Impact Positive Human Impact

Runoff and Pollution Artificial Reefs

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Dichotomous Keys

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Dichotomous Key• Dichotomous – Greek for “divided into two parts”• A tool used to help a user identify living and non-living things• Can be a series of questions or more like a chart with choices

How to use a Dichotomous Key• Choose an organism or structure to identify• Read the first set of choices on the dichotomous key• Decide which statement is true and follow the directions for that statement• The directions will lead to a new set of choices• Continue the process until you have identified the organism or structure

Reading a Dichotomous Key - Practice

A B C D E F

1. a. Organism is a vertebrate……………………………………………………..……….….go to 2b. Organism is an invertebrate…………………………………….….……….…….…….go to 4

2. a. Organism has wings……………………………………………………………………………..………batb. Organism does not have wings…………………………………………………………go to 3

3. a. Organism has legs………………………………………………………………………………….go to 4b. Organism does not have legs……………………………………………………….………snake

4. a. Organism has antenna…………………………………………………………,………………………antb. Organism does not have antenna…………………………………………………….go to 5

5. a. Organism has a shell…………………………………………………………………….…….tortoiseb. Organism does not have a shell……………………………………………….………go to 6

6. a. Organism has a tail……………………………………………………………………..……………lizardb. Organism does not have a tail………………………………………………..………….spider

Use the dichotomous key above to identify organisms A-F. Write your answers in the boxes below.

Organism A = Organism B = Organism C =

Organism D = Organism E = Organism F =

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Natural Selection

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Natural Selection• Organisms that are better suited for their environment are more likely to survive and reproduce• Charles Darwin - naturalist known for his contributions to the theory of evolution by natural selection• Darwin observed a large variety of species on the Galapagos Islands• He concluded many of the different species had adaptations that allowed them to be better suited

for their environment• The beaks of Galapagos finches were different shapes and sizes to suit their diets on the different

islands

Adaptations• Characteristics that help organisms survive in their environment and reproduce• Structural – a type of adaptation that makes up the physical features of an organism that help it

survive • Behavioral – a type of adaptation that can be instinctive or learned and deals with the way an

organism acts in order to survive• Physiological – a type of adaptation that allows an organism to perform special functions within its

body

Galapagos IslandsCharles Darwin

Galapagos Finch

Structural – Long legs Behavioral - Migration Physiological - VenomSelective Breeding• The intentional breeding of two individuals to produce offspring with favorable characteristics • Can be used to eliminate certain characteristics• Examples: Dogs are bred for temperament and a variety of other traits; angus cows are bred for meat

production; bananas are bred to be sweeter and larger

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Sexual vs. Asexual Reproduction

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Sexual Reproduction• Requires two parents• Each organism has specialized sex cells• Occurs when male and female sex cells fuse together• Offspring have characteristics of both parents, but are not identical• Advantages; more genetically diverse offspring, more adaptability, greater variation, better chance

of surviving when faced with environmental changes• Disadvantages: requires two individuals, requires a large amount of energy to nourish offspring before

and after birth

Asexual Reproduction• Requires only one parent• Offspring have characteristics genetically identical to parent• Most common in single celled organisms, but can occur with more complex organisms such as sea

stars or worms• Advantages: quick population growth, less energy to reproduce, all organisms are able to reproduce• Disadvantages: no genetic diversity, organisms are not easily able to adapt to environmental

changes

Types of Asexual Reproduction• Binary Fission – a cell dividing into two cells after duplicating its genetic material• Budding – an organism forming a growth that develops into a genetically identical organism and

then breaks off• Fragmentation – an organism splits into pieces and each piece develops into a genetically identical

organism

Sexual Reproduction

Humans Penguins

Monkeys

Asexual Reproduction

HydraStrawberries

Planarian

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Plant Cells

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Plant Cells• Rectangular shape• Contain a cell wall and chloroplasts• One large vacuole to store water for structure and support• Examples of organisms containing plant cells: trees, grass, shrubs, and ivy

Plant Cell Structures and Functions• Cell Membrane – controls what comes in and out of the cell • Cell Wall – rigid layer surrounding a plant cell that provides support, strength, and shape • Nucleus – controls the activities of the cell • Cytoplasm – thick gel-like fluid inside the cell between the nucleus and the cell membrane • Mitochondria – produces the energy needed for the cell to carry out its functions • Chloroplast – contains chlorophyll and makes food from sunlight • Vacuole – the storage area of the cell • Golgi Bodies – packages and distributes materials to other parts of the cell • Endoplasmic Reticulum – passageways in the cell that carry materials from one part of the cell to

another

Cell WallMitochondria

Vacuole

Chloroplast

Nucleus

Endoplasmic Reticulum

Golgi Bodies

Cell Membrane

Cytoplasm

Structures of a Plant Cell

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Animal Cells

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Animal Cells• Generally have a circular or irregular shape• Contain all the same organelles as a plant cell except for a cell wall and chloroplasts• Many smaller vacuoles than a plant cell• Examples of organisms containing animal cells: humans, dogs, elephants, and birds

Animal Cell Structures and Functions• Cell Membrane – controls what comes in and out of the cell • Nucleus – controls the activities of the cell • Cytoplasm – thick gel-like fluid inside the cell between the nucleus and the cell membrane • Mitochondria – produces the energy needed for the cell to carry out its functions • Vacuole – the storage area of the cell • Golgi Bodies – packages and distributes materials to other parts of the cell • Endoplasmic Reticulum – passageways in the cell that carry materials from one part of the cell to

another

Structures of an Animal Cell

Cell Membrane

Vacuole

Golgi Bodies

Mitochondria

Nucleus

Cytoplasm

Endoplasmic Reticulum

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Inherited and Acquired Traits

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Inherited Traits• A trait that an organism is born with that is obtained from parents or ancestors• Determined by information found in the genes within chromosomes inside the nucleus of cells• Gene - a segment of DNA that has the code for a specific trait • Chromosome - the location where genetic information is stored within the nucleus of a cell• Examples of inherited traits - hair color, hair texture, dimples, freckles, tongue rolling

Inherited Traits

Tongue rolling Earlobes Hair color

Acquired Traits• A trait that an organism obtains during its lifetime through its environment• Characteristics that are learned or happen to an organism during its life• Examples of acquired traits - muscle size, pierced ears, learning to read or ride a bike, scars

Acquired Traits

Muscle size Learning to ride a bike Learning to read

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Levels of Organization

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Levels of Organization• Cell – the basic unit of life• Tissue – a group of similar cells that do the same sort of work• Organ – a group of tissues that work together to perform a specific function• Organ System – a group of organs that work together to perform a specific function • Organism – a living individual that can reproduce, grow, and maintain homeostasis

Cell Tissue Organ Organ System Organism

Levels of Organization

Cell Theory• Composed by German scientists Matthias Schleiden, Theodor Schwann, and Rudolf Virchow• Consists of three main parts:1. Cells are the basic unit of life

2. All living things are made up of one or more cells3. Cells arise (come from) other living cells

Theodor SchwannMatthias Schleiden Rudolf Virchow

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Characteristics of Organisms

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Prokaryote vs. Eukaryote• Prokaryote – an organism whose cells lack a nucleus and other organelles• Examples of prokaryotes – bacteria such as Staphylococcus Aureus and Escherichia coli• Eukaryote – an organism whose cells contain a nucleus and other organelles• Examples of eukaryotes – humans, plants, and animals

• Remember – Pro = NO nucleus; Eu = TRUE nucleus

Prokaryotic Cell Eukaryotic Cell

Unicellular vs. Multicellular• Unicellular – an organism that is made up of only one cell• Examples of unicellular organisms – amoeba, paramecium, and euglena• Multicellular – an organism that is made up of many cells• Examples of multicellular organisms – trees, ants, and mushrooms

Unicellular Multicellular

Autotroph vs. Heterotroph• Autotroph – an organism that is able to produce its own food through the process of photosynthesis• Examples of autotrophs – grass, trees, and algae• Heterotroph – an organism that must consume other organisms in order to obtain energy• Examples of heterotrophs – grasshoppers, snakes, and bears

Autotroph Heterotroph

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Body Systems

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Body System Function Structures Diagram

CirculatorySystem

Transports oxygen and nutrients to the body and removes CO2 and other waste products

arteries, veins, and capillaries

RespiratorySystem

Supplies the blood with oxygen in order for the blood to deliver oxygen to all parts of the body

trachea, bronchi, and lungs

SkeletalSystem

Provides support, movement, protection, blood cell production, and calcium storage

femur, humerus, clavicle, skull, and ribs

MuscularSystem

Responsible for the movement of the human body

biceps, triceps, deltoid, and trapezius

DigestiveSystem

Breaks down food into tiny molecules to allow the body to absorb nutrients

stomach, intestines,and liver

ExcretorySystem

Removes wastes that can cause toxic build up and lead to diseases or death

kidneys, ureter, and urethra

ReproductiveSystem

Produces eggs or sperm and nourishes offspring until birth

uterus, ovaries, and testes

IntegumentarySystem

Acts as a barrier to protect the body from the outside world

skin, hair, and nails

NervousSystem

Controls and transmits signals between different parts of the body

brain, spinal cord, and nerves

EndocrineSystem

Glands that secretehormones to regulate metabolism, growth, sleep, and reproduction

pituitary gland, thyroid gland, and adrenalgland