Name: ______
Midterm Proficiency Study Guide
7th Grade Science – Miss Maxwell & Mr. Burgmeyer
Exam Dates: Wed. 1/28 and Thurs 1/29 Period: ______
1. What is an atom? List and describe the three parts of an atom.
The smallest particle/the building block of matter. The three particles inside an atom are the proton (positive charge, found in the nucleus), the neutron (neutral charge, found in the nucleus), and the electron (negative charge, found outside the nucleus in the electron cloud)
2. What makes an atom of one element different from an atom of another element?
Each atom has a specific number of protons in its nucleus, atoms of different elements have different atomic numbers and therefore different numbers of protons.
3. What is a physical property? Give 2 examples.
A characteristic of matter that can be observed or measured without changing the matter. Density and mass.
4. What is a physical change? Give 2 examples.
A physical change, changes the appearance of matter, but NOT the identity of the matter. Changes in state, crushing ice
5. What physical property of matter can be used to identify unknown substances?
Density can be used to identify unknown matter, as all materials have a unique density, and density is size-independent which means it will not change with the size of a sample.
6. What is a chemical property? Give 2 examples.
Chemical properties are properties of matter that can only be observed as matter undergoes a chemical change. Ability to burn, ability to rust.
7. What is a chemical change? Give 2 examples.
A change in matter in which new substances are formed, and the identity of the matter changes. Burning, rusting
8. What is a chemical equation? How do you write one? What are reactants and products?
A chemical equation shows all the chemical formulas involved in a chemical reaction. To write a chemical equation, you must make sure that the number of atoms of each element are balanced on both sides. Reactants are the substances that undergo the chemical change, products are the substances both old and new formed after a chemical reaction has occurred.
9. What is the law of mass conservation? How does this relate to the masses of the reactants and products of a reaction?
The law of conservation of mass states that mass before and after a change is the same. The mass of the products in a chemical equation must be equal to the mass of the reactants.
10. What is potential energy? Give 2 examples.
Energy stored inside an object, due to position. A clock on the wall, a book on a shelf
11. What is kinetic energy? Give 2 examples.
Energy an object has due to its motion. A skier riding down a hill, a car driving on the road.
Type of Energy / Definition / Examplechemical / Energy stored in and released in the bonds between atoms. / Food
nuclear / Energy stored in and released from the nucleus of an atom / Nuclear power plant, the Sun
electrical / Energy that flows in an electric current / Electrical outlet
sound / Energy that travels in sound waves / Singing
radiant / Energy that travels in electromagnetic waves / microwaves
thermal / The sum of kinetic and potential energy in the particles of an atom / Heating or cooling particles in an object
mechanical / The sum of kinetic and potential energy within a system / A football thrown through the air
12. Compare the movement and energy of the particles at a cold temperature and a warm temperature.
Particles at a cold temperature move slowly and are packed close together, particles at a warmer temperature spread out and move faster.
13. What is an energy transfer? Give an example.
When energy moves from one object to another without changing form. A tennis player uses mechanical energy to swing a tennis racket and transfers that mechanical energy to the ball when the racket makes contact.
14. What is an energy transformation? Give an example.
When energy changes from one form to another. When food is digested its chemical energy is stored in your body and then later transforms into mechanical energy to move your muscles.
15. What does the law of conservation of energy state?
Energy cannot be created or destroyed, only transferred and transformed.
16. What is a reference point?
An initial or starting point, used to describe the motion of an object.
17. What is the formula for speed?
Speed = distance/time
18. Solve for speed in a car traveling 50 meters in 100 seconds.
Speed = 50 meters/100 seconds = .5 m/s
19. On a speed vs. time graph what represents an object at rest? accelerating? decelerating?
At rest- a horizontal line
Accelerating – a slanted line, slopping from lower left to upper right
Decelerating – a slanted line, slopping from upper left to lower right
20. How do you determine net force if forces act in the same direction? Opposite directions?
If the objects are acting in the same direction, add the net forces together. If the objects are acting in the opposite directions, subtract the smaller force from the larger force, the direction will be that of the larger force.
Organelle / Function / Plant, Animal, or bothChloroplasts / Conducts photosynthesis / Plant
Cell membrane / Flexible covering that allows things in and out of the cell / Both
Vacuole / Stores water, waste, and food / Both
Golgi apparatus / Packages proteins inside the cell before they are sent to their destination / Both
Endoplasmic reticulum / Smooth: make lipids such as cholesterol
Rough: makes proteins / Both
Nucleus / Directs cell activity; “Brain of the cell” / Both
Cell wall / Protect the plant structural support and protects the plant cell / Plant
Ribosomes / Responsible for assembling the proteins of the cell / Both
Mitochondria / Energy for the cell; “Powerhouse of the cell” / Both
21. List and describe the levels of organization in a multicellular organism beginning with a single cell.
Cells are organized into tissues. Tissues are groups of similar types of cells that work together to carry out specific tasks. Organs are groups of different tissues working together to perform a particular job. Organ systems are groups of different organs that work together to complete a series of tasks.
22. Compare asexual and sexual reproduction.
Asexual reproduction is when one parent organism produces offspring without meiosis and fertilization. Because offspring inherit all their DNA from one parent, they are genetically identical to each other and to their parent.
Sexual reproduction is when the genetic materials from two different cells combine, producing an offspring. Because offspring inherit their DNA from both parents, there is genetic variation among offspring.
23. Compare the number of chromosomes in a diploid and haploid cell.
In a diploid cell there are 46 chromosomes. In a haploid cell there are 23 chromosomes.
Genetics Vocabulary / Definitionhomozygous / When two alleles of a gene are the same
heterozygous / When two alleles of a gene are different
dominant / A genetic factor that blocks another genetic factor; expressed using a capital letter
recessive / A genetic factor that is blocked by the presence of a dominant factor; expressed using a lower case letter
phenotype / How a trait appears, or is expressed
genotype / The two alleles that control that phenotype
24. A child has blue eyes, but both of the child’s parents have brown eyes. Create a Punnett Square below that explains how this is possible. (B represents brown eye allele, b represents blue eye allele)
B b
B
Write a sentence to explain the Punnett Square you created.
One possible offspring would be homozygous dominant (BB), 2 would be heterozygous (Bb) and one would be homozygous recessive (bb) which is how a child has blue eyes.
25. Where does the energy in an ecosystem initially come from?
From the sun
26. What is the difference between biotic and abiotic factors in an ecosystem? Give some examples of each.
Biotic factors are all the living or once-living things in an ecosystem. Examples are populations and communities
Abiotic factors are the nonliving parts of an ecosystem. Examples are water, light, temperature, atmosphere, and soil.
27. List and describe the three types of symbiotic relationships.
Mutualism: two species in a community benefit from the relationship.
Parasitism: one species (the parasite) benefits while another (the host) is harmed.
Commensalism: one species benefits and the other is neither helped nor harmed
ECR practice: Answer all three questions
1. All matter has both physical and chemical properties, when matter undergoes a change it can be either physical or chemical.
· Define physical property and chemical property and give an example for each
· Define physical change and chemical change and give an example for each
· What makes the difference between a property of matter and a change in matter?
A physical property is a characteristic of matter that you can observe or measure without changing the identity of the matter(boiling/melting point). A physical change is a change in the size, shape, form, or state of matter that does not change the matter’s identity(melting ice, mowing the lawn, carving a statue). Chemical property is the ability of a substance to combine with or change into one or more new substances( ability to rust, ability to burn, ability to rot). A chemical change is the change in matter in which the substances that make up that matter change into other substances with different chemical and physical properties(burning a log, rotting apple, rusted bike chain).
2. Sunlight is absorbed by a solar panel on a house. The energy collected by the solar panel is used to run a blender that chops apples. The apples are part of a recipe that is cooked in the oven.
· What is an energy transfer?
· What is an energy transformation?
· Explain the scenario above in terms of the types of energy involved and the energy transfers and transformations involved.
An energy transfer is when energy moves from one object to another without changing form. Energy transformations is when energy moves from one object to another and changes its form. The solar panels collect radiant energy. Radiant energy from the panels is transformed into electrical energy to the blender. The electrical energy in the blender is transformed into mechanical energy to chop the apples. The apples are placed in the oven where thermal energy from the oven in transferred to the apples, heating them.
3. A heterozygous orange-flowered plant is crossed with a homozygous purple-flowered plant.
· Create a Punnett Square that shows the possible offspring
· If orange is a dominant allele and purple is recessive, what color ratio will the flowers of the offspring plants have? Explain.
D d
Dd / ddDd / dd
There would be a 2:4 chance that the flowers would be orange and a 2:4 chance that the flowers would be purple. Two of the flowers would be heterozygous resulting in orange flowers and 2 would be homozygous recessive resulting in purple flowers.