Science Study Guide for the HiSET Test

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General Information

When you take this test, you will have 80 minutes to answer 60 multiple-choice questions. A great many of these questions will refer to given passages or visual stimuli, such as graphs, charts, and tables. You will need to combine your skill in reading and comprehending these with the basic science knowledge you gained through high school level studies to find the correct answers. While knowledge of science content will be helpful, you also need to be comfortable with the experimental process and use process skills when answering.

The content covered in the questions comes from these areas of science, in approximately these percentages:

  • Life Science (49%)
  • Physical Science (28%)
  • Earth Science (23%)

In this study guide, we will focus on the content first. You will not be able to get all the information you need in this guide, but you will have an idea of the topics and concepts you’ll need to know. Following that, we will outline the types of scientific processes and terms you’ll need to know. Be sure to seek extra help and practice with any content or procedures that give you trouble. Use our practice tests and flashcards for more information about just where you stand with science before taking the test.

We have provided a list of terms, where appropriate. One effective study procedure would be to create flashcards or a study process on your device that involves matching these terms to definitions you provide, according to reputable sources. Science textbooks are a valuable tool for this type of test preparation.

Science Content

Each question on the HiSET® Science test will come from one of the three following areas of science. Be sure you are familiar with the topics and terms we have listed here. Again, if you appear to need further instruction or understanding, consult the many available online sources and access current textbooks and workbooks, as well as educational professionals to help you.

Life Science

Life science is the study of living organisms. This might include the study of the means by which they stay alive, how they reproduce, and how they are classified. Examples of life sciences include biology, botany, zoology, microbiology, ecology, and genetics.


Organism refers to any living being. Organisms are classified into five kingdoms: plants, animals, fungi, protists, and monera (bacteria and cyanobacteria).


An organism’s environment is the collection of all living and nonliving factors that surround it. Nonliving or abiotic factors may include temperature, moisture, and water conditions. Living or biotic factors are the other organisms that it interacts with. The environment provides the conditions to which the organism must adapt in order to survive and reproduce.

Life Cycles

An organism’s life cycle consists of stages of growth and maturity it must complete to survive and reproduce. In general, it involves some form of birth or hatching, development to maturity, and reproduction. Common life cycles are egg-larva-pupa-adult for insects and egg-tadpole-adult for frogs.


Organisms commonly depend on other organisms for food and/or shelter, and perhaps other requirements for survival. Some specific forms of interdependence, also called symbiosis, are mutualism, commensalism, and parasitism.

Important Terms and Ideas: classification, order, family, genus, species; ecosystem, biome, habitat, niche; food webs, trophic levels, nutrient cycling, herbivore, carnivore, omnivore; genetics, gene, DNA, RNA, dominant, recessive; evolution, survival of the fittest; mitosis, meiosis, sexual and asexual reproduction

Living Systems

Organisms are considered to be living systems of structures and functions that maintain life and produce a new generation to ensure the survival of the species.


Organisms develop a wide range of structures that are specialized to perform the functions needed to keep the organism alive. Some examples are cell membranes, roots in plants, and nervous systems in animals.


The survival of an organism depends on the maintenance of many biological functions. Some of these functions include growth, regulation of proper internal factors such as pH, procurement or production of energy and oxygen, distribution of these resources throughout the organism, and reproduction.

Important Terms and Ideas: homeostasis; respiration, aerobic, anaerobic; circulation; photosynthesis; communication; reproduction; cells, tissues, organs, organ systems

Human Body Systems

Human body systems consist of organs which in turn consist of specialized cells. Each organ performs a specific function, and together these organs form a system that completes a vital process in maintaining our health. The need for specialized functions means that each organ is a separate structure devoted to the performance of a specific function.

Nervous System

The nervous system collects information from sense organs and other organ systems and coordinates the response to changing conditions. Messages sent through the nerves cause muscles to contract and may also stimulate responses from other systems.

Important Terms and Ideas: brain, nerves, synapse, neurotransmitters

Endocrine System

The endocrine system uses chemical messengers called hormones to communicate with organs throughout the body and regulate important functions. The hormones are carried by the circulatory system.

Important Terms and Ideas: hormones, adrenaline, sympathetic and parasympathetic systems, epinephrine

Circulatory System

The circulatory system delivers oxygen, nutrients, and hormone messengers throughout the body and transfers waste products to the kidneys for excretion.

Important Terms and Ideas: blood; heart, atrium, ventricle; arteries, veins, capillaries; lymph

Digestive System

The digestive system includes organs for the ingestion of food and the breakdown of the food into simple nutrients that can be used throughout the body. It also includes organs for the elimination of leftover solid waste after digestion is complete.

Important Terms and Ideas: mouth and saliva, esophagus, stomach, pancreas, liver, small and large intestines

Respiratory System

The respiratory system is responsible for bringing air into the body, extracting oxygen for delivery throughout the body, and removing waste carbon dioxide from the bloodstream.

Important Terms and Ideas: lungs and trachea

Renal System

The renal system consists of the kidneys, which filter or remove waste compounds from the bloodstream and the urinary tract, which eliminates these waste compounds from the body.

Important Terms and Ideas: nephrons

Immune System

The immune system protects the body from disease-causing pathogens. The cells of the immune system circulate in the bloodstream and lymphatic fluids surrounding cells and tissues. These cells identify and destroy pathogens.

Important Terms and Ideas: antigen and antibody, white blood cells, T cells, autoimmune diseases

Skeletal/Muscular System

This system supports the body with bones and enables the body to move through muscular action.

Important Terms and Ideas: bones; muscle, striated muscle, smooth muscle; cartilage; tendons, ligaments

Reproductive System

The reproductive system includes the production of sperms and eggs, the means of fertilizing the eggs, and the development of the embryo.

Important Terms and Ideas: testes, ovaries, placenta

Integumentary or Exocrine System

The integumentary system consists of the skin, the largest organ of the body. The function is to protect the body from damage and to prevent excessive loss of water from the body.

Important Terms and Ideas: epidermis, follicles, dermis, sweat glands


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