Science - 1st Term Exam | Reviewer

chemical reaction

A __ occurs when reactant particles collide with enough energy and in the correct orientation.

Reaction Rate

How fast a chemical reaction happens.

Temperature

A factor that affects reaction by changing the kinetic energy and movement of particles.

Concentration

The amount of reactant particles present in a given volume.

Surface area

The amount of exposed surface of a solid reactant available for contact and reaction.

Pressure

A factor that mainly affects gases; increasing pressure forces particles closer together.

Inhibitor

A substance that slows down a chemical reaction; also called a negative catalyst.

Nature of the Reactants

The chemical properties of reactants that affect how quickly they react.

Photochemical Reaction

A chemical reaction that requires light energy or happens faster when exposed to light.

Collision

when particles hit one another.

Catalyst

a substance that speeds up a reaction without being used up.

Polymer

a large molecule made of repeating smaller units.

Activation energy

the energy required for a reaction to occur.

Refrigeration

__ slows oxidation and enzyme activity, helping preserve food.

Freezing

__ slows spoilage even further because much of the water becomes ice. This limits reactions and microbial growth, while particle movement becomes very slow.

Higher temperature

__ increases particle movement. Heated particles move faster and collide more often with greater energy, increasing the reaction rate.

Combustion

__ is a rapid chemical reaction that occurs when fuel reacts with oxygen and releases heat and light.

Heat

raises the fuel to its ignition temperature.

Oxygen

supports the burning process.

Fuel

the material that burns, such as wood, paper, or gasoline.

Corrosion

__ is the gradual destruction of metals when they react with substances in the environment.

Rusting

__ is a common type of corrosion involving iron.

lower

Catalysts can help reduce harmful pollutants because they __ activation energy, allowing reactions to happen more quickly and efficiently.

Catalytic converters

__ are used in vehicles and are placed in the exhaust system to treat gases produced by engines.

Exothermic Reaction

releases heat to the surroundings.

General Equation:

Reactants → Products + Heat

Heat is on the product side because heat is released.

Example:

CH₄ + 2O₂ → CO₂ + 2H₂O + Heat

The surroundings become warmer.

Endothermic Reaction

absorbs heat from the surroundings.

General Equation:

Reactants + Heat → Products

Heat is on the reactant side because heat must be absorbed.

Example:

CaCO₃ + Heat → CaO + CO₂

Homeostasis

__ is the ability of the human body to maintain a stable internal environment despite changes inside or outside the body.

It keeps body conditions within a normal range so that cells, tissues, and organs can function properly.

fluid balance

__ helps maintain the proper amount of fluid in the body.

Nervous system

detects changes and sends signals.

Endocrine system

releases hormones that regulate body processes.

Receptors

Detect changes in the internal or external environment.

Control Center

Receives and processes information and determines the appropriate response. It is often the brain or an endocrine gland.

Effectors

Muscles or glands that act to return conditions to the set point.

set point

The __ is the normal or target condition the body tries to maintain.

37 degree celsius

The body normally maintains a temperature close to __, although it may change slightly during the day.

Hypothalamus

The __, located in the brain, acts as the body's temperature-control center.

High

When Body Temperature Is Too __

• Sweat glands produce sweat.

• Sweat evaporates and removes heat from the skin.

• Blood vessels near the skin widen to release more heat.

Low

When Body Temperature Is Too __

• Muscles contract rapidly, causing shivering.

• Blood vessels near the skin narrow to reduce heat loss.

• The body increases heat production.

These responses return body temperature to its normal range.

Blood pressure

__ is the force of blood pushing against the walls of blood vessels.

baroreflex

The __ quickly adjusts heart rate and blood vessel width to help maintain normal blood pressure.

Low

When Blood Pressure Is Too __

• The heart may beat faster.

• Blood vessels narrow.

• More blood is directed toward important organs.

High

When Blood Pressure Is Too __

• Blood vessels may widen.

• The heartbeat may slow down.

• The kidneys may remove more water and salt from the body.

Blood glucose

__ is the amount of glucose or sugar in the blood.

Glucose

__ provides energy needed by the body's cells.

pancreas

The __ regulates blood glucose by releasing two hormones: Insulin & Glucagon

Insulin

Lowers blood glucose levels.

Glucagon

Helps raise blood glucose when it becomes too low.

High

When Blood Glucose Is Too __

1. The pancreas releases insulin.

2. Body cells take in glucose for energy.

3. The liver stores excess glucose.

4. Blood glucose returns toward its normal range.

Low

When Blood Glucose Is Too __

1. The pancreas releases glucagon.

2. The liver releases stored glucose into the blood.

3. Blood glucose returns to its normal range.

Insulin

After eating rice or bread → blood glucose increases → __ is released.

glucagon

After not eating for several hours → __ helps release stored glucose.

Negative feedback

__ reverses a change to bring the system back to normal balance.

Positive Feedback

__ amplifies the initial change to push a process to completion.

Favorable trait

a characteristic that helps an organism survive or reproduce.

Competition

the struggle among organisms for limited resources.

Inherited traits

characteristics passed from parents to offspring.

Natural selection

the process where organisms with traits best suited to their environment are more likely to survive and reproduce.

Evolutionary Change

__ refers to changes in the inherited characteristics of a population over many generations.

Variation

__ refers to differences among organisms of the same species.

Heredity

__ is the passing of genetic information from parents to offspring.

Gregor Mendel

__ is known as the Father of Genetics.

He studied inheritance using pea plants. His experiments helped explain how traits can pass from parents to offspring.

Inherited Characteristics

Characteristics passed through genes from parents to offspring.

Example: A Labrador puppy may inherit genes that influence its coat color.

Acquired Characteristics

Characteristics developed during an organism's lifetime and are not genetically passed to offspring.

Example: If a dog gets a scar from an injury, the scar will not be genetically passed to its puppies.

mutation

 __ is a change in DNA.

Genetic Recombination

Sexual reproduction produces new combinations of parental genes.

Example: Human siblings from the same parents may inherit different combinations of traits.

Isolation

__ is the separation that limits interaction or reproduction between populations.

Speciation

__ is the formation of new species over time.

Interbreeding

__ is reproduction between individuals from different populations or groups.

Ernst Mayr

__ emphasized the importance of geographic isolation in speciation.

Separated populations may experience different conditions and gradually become more different over time.

Geographic isolation

__ occurs when a physical barrier separates populations.

Gene flow

The movement or exchange of genetic information between populations; geographic barriers can limit it.

Reproductive Isolation

__ occurs when populations do not normally reproduce successfully with one another.

adaptation

An __ is an inherited characteristic that improves survival or reproduction in a particular environment.

Peter and Rosemary Grant

__ and __ conducted long-term studies of Galápagos finches. They observed changes in finch populations following changes in rainfall and food availability.

Their work demonstrated natural selection occurring in wild populations.

Structural adaptations

Physical features that improve survival.

Examples:

• Polar bears – thick fur and a layer of fat reduce heat loss in Arctic conditions.

• Cacti – spines and thick stems reduce water loss and store water.

• Ducks – webbed feet help them push against water while swimming.

Behavioral adaptations

Behaviors that improve survival or reproduction.

Examples listed in the material include:

• Kangaroo rats producing very concentrated urine to conserve water in deserts.

• Rattlesnakes producing venom to help subdue prey.

• Some Antarctic fish producing antifreeze proteins to prevent body fluids from freezing.