Page 1 General Science Study Guide for the ASVAB

How to Prepare for the ASVAB General Science Test

General Information

The General Science section of the ASVAB test is designed to measure your scientific aptitude. Because it is a general science test, students must possess a general knowledge of a variety of scientific areas, including ecology, astronomy, anatomy, geology, and biology. When studying for each of these portions of the general science test, be sure not to focus too heavily on any one area; a basic understanding of and knowledge in these areas is all that is required. Each separate category will be discussed in greater depth here.

Life Science

Health and Nutrition

Micro and Macronutrients

Micronutrients consist of those vitamins and minerals required by the body to function properly. As indicated by the micro- prefix, these nutrients are only required in small amounts; however, they are not insignificant. If adequate amounts of these micronutrients are not acquired, health is potentially compromised, and long term issues may arise.

Macronutrients consist of those larger compounds from which we derive the calories, or energy, necessary to sustain life functions. Carbohydrates, proteins, and lipids (or fats) are the macronutrients from which our energy is derived.

Carbohydrates, both simple and complex, can be thought of as immediate and readily accessible energy. These molecules are ultimately broken down into glucose and circulated throughout the blood to support metabolic functions.

The body converts and stores unused carbohydrates as lipids, or fats. Lipids function as the source material for hormones. They enable the better absorption of micronutrients, and they also serve as an energy source.

Protein is necessary for cellular growth, repair, and transport. Proteins are made up of amino acids, which can be thought of as micronutrients.

Related terms to know: vitamins, minerals, carbohydrates, lipids, proteins

Nutrition-Related Diseases

Nutrition-related diseases are those which arise from either the deficiency or the excess of a micro or macronutrient. Diabetes, hypertension, scurvy, and iron-deficiency anemia are examples of nutrition-related diseases.

The Human Body

Human anatomy is the study of the human body: how it works, what makes up its parts, and what is necessary to keep it functioning well and properly. Human anatomy is included in the General Science section of the ASVAB, requiring students to have a basic knowledge and understanding of the human body and its functions. To prepare for this, study the basic components of human anatomy, including the bones, muscles, and blood vessels comprising the body, as well as the basic functions of these different systems. Though the questions are not heavy or in-depth due to the “general” nature of the test, you should have some understanding of how the body works and what is required to keep it functioning.

Skeleton and Muscles

The human skeletal system is a collection of bones, composed of a very hard and inflexible phosphate, and cartilage, composed of spongy, flexible collagen. The skeletal system functions as structural support and protection for muscles and organs. It also facilitates locomotion. Blood is created inside of bone marrow.

The muscular system works in conjunction with the skeletal system to facilitate motion. The muscular system is made up of three types of muscle: cardiac muscle, skeletal muscle, and smooth muscle.

The heart is made of cardiac muscle that transmits electrical signal to trigger heart beats.

Skeletal muscles are those connected to bone that enable motion.

Smooth muscle lines organs and aids in digestion.

Related terms to know: bones, cartilage, cardiac, skeletal, smooth

Blood and Circulation

The circulatory system is responsible for the transport of blood and nutrients throughout the body. It is made up of arteries, veins, capillaries, the lungs, the heart, the brain, and the kidneys.

The heart functions to pump oxygenated blood to the body and deoxygenated blood to the lungs to become oxygenated. Blood flows through the arteries and veins along with other nutrients, while delivering oxygen to cells throughout the body and carbon dioxide to the lungs to be eliminated.

Blood consists of red blood cells which facilitate oxygenation, white blood cells which aid in immunologic defense, plasma which is the liquid medium inside of the circulatory system, and platelets which also aid in defense.

Cardiovascular diseases stem from difficulties in pumping blood throughout the body by way of arterial blockage, high blood pressure, and other issues.

Related terms to know: blood, arteries, veins

Digestion and Excretion

The digestive system functions to break food down into useable micro and macronutrients. Upon ingestion of food, the digestive process begins.

The saliva in our mouths contains enzymes that begin breaking down food. Mastication, or chewing, helps reduce the food to a bolus that is easy to swallow.

Smooth muscle in the esophagus undergoes peristalsis to pass the bolus to the stomach where the bolus is treated with strong acids to create chyme, which is then passed onto the small intestine.

The small intestine primarily serves to absorb the nutrients from the chyme before passing it on to the large intestine. In the large intestine, further absorption of nutrients and water takes place, before passing the remaining matter, termed feces, to the rectum where it is excreted through the anus.

The excretory system serves to expel waste, primarily urine, from the body. This system helps maintain homeostasis through the regulation of internal fluids. Its major components are: kidneys, lungs, skin, ureter, urethra, and the urinary bladder.

The kidneys function to remove waste from the bloodstream through a filtration system resulting in the production of urine.

The lungs, in addition to providing oxygenated blood, remove carbon dioxide from the blood.

The skin is the organ through which perspiration is released. It plays a minor role in excretion; its primary role is temperature regulation.

The ureter, urethra, and urinary bladder all work in conjunction to remove and expel urine from the body.

Related terms to know: organs

Nervous System

The nervous system enables communication between cells throughout the body. Its major components are the brain, the spinal cord, and neurons, or nerve cells.

The brain acts as the central information processing unit of the body. It is composed of many billion neurons and it is where information received by the senses is processed. The brain contains two hemispheres and three major parts: the cerebrum, the cerebellum, and the brain stem.

The cerebrum serves to control the senses. The cerebellum aids in balance and coordination. The brain stem connects with the spinal cord and regulates involuntary movements such as breathing and digestion.

The neurons that make up the brain contain a nucleus and long branches that extend to other neurons. Chemical signals pass from one neuron to the next to transmit information.

The spinal cord connects the brain to the rest of the body. It is a bundle of nerves that runs vertically through the spine that branches throughout the body. Signals received by the senses travel through the spinal cord to be processed in the brain.

Together, the brain and the spinal cord form the central nervous system. The peripheral nervous system is the collection of nerves residing outside of the central nervous system.

Related terms to know: neurons, brain, spinal cord, central nervous system, peripheral nervous system

Reproduction

Reproduction exists in two forms: asexual and sexual. Asexual reproduction requires no partner, and the offspring produced inherits the same genes as the parent. This differs from sexual reproduction, in which there are usually two partners who both contribute equally to the genetic makeup of the offspring.

Asexual reproduction is the method by which somatic, or body, cells divide. Through mitosis, a cell divides, and both daughter cells possess the exact DNA of the parent cell.

Meiosis is the process by which sex cells divide. This process results in cells that contain genetic material that is partially from one parent cell and partially from a different parent cell.

Related terms to know: meiosis, mitosis, cellular division, sexual reproduction, asexual reproduction

Genetics

Genetics is the study of genes, the portions of DNA that result in genotypic and phenotypic traits that are passed from one generation to the next. An organism’s genotype is its genetic makeup, which includes both dominant and recessive alleles (or variation of a gene). An organism’s phenotype is the physical expression of its genotype.

Dominant traits are those that are expressed when a person has two types of alleles. Recessive traits are those that go unexpressed unless a person possesses both recessive alleles.

Deoxyribonucleic acid (DNA) is the nucleic acid containing the nucleotides adenine, guanine, thymine, and cytosine that provides the blueprint for cell replication. Variations in DNA account for the different genetic and physical traits of organisms.

Meiosis and mitosis are the processes by which cells replicate. Sex cells undergo meiosis, which combines the genes of two individuals to produce a new genotype. Somatic, or body, cells undergo mitosis and create two daughter cells with the same genotype as the parent cell.

Humans have 23 pairs of chromosomes, or tightly wrapped strands of DNA, that provide the instructions for metabolic processes, building cellular and tissue components, as well as other body functions. One pair of chromosomes is linked to sex: females exhibit a homozygous XX chromosome and males exhibit a heterozygous XY chromosome.

A Punnett square can be used to determine the potential genotypes of offspring between two parents. It is a large square with four (or more) squares inside, with the rows and columns corresponding to the alleles of the parents. Two heterozygous parents are shown with a capital letter and a lowercase letter along the left and right columns and down the top and bottom rows. The offspring genotypes are found by filling in the four (or more) boxes with the letters found at the top and to the left of the Punnett square. Heterozygous parents produce two homozygous offspring, one AA, one aa, and two heterozygous offspring, Aa.

Related terms to know: genes, chromosomes, alleles, meiosis, mitosis, Punnett square

Cells

Cells are the most basic structural unit of life. Prokaryotic cells are those that do not contain a membrane-bound nucleus or organelles; they are single-celled organisms. Bacteria are an example of a prokaryote. Eukaryotic cells are those that contain a membrane-bound nucleus in addition to other organelles; they are single-celled or multicelled organisms. Humans are eukaryotic.

The genetic material of prokaryotes floats openly throughout its cytoplasm, whereas the genetic material of eukaryotes is found inside of the nucleus. Prokaryotes undergo binary fission to replicate, and eukaryotes undergo meiosis and mitosis to replicate.

Animal cells are different from plant cells in the organelles they contain. Organelles are analogous to organs in humans and perform the tasks necessary to preserve the metabolic function of the cell.

Plant cells contain a cell wall, plastids, and chloroplasts, which enable plants to produce energy through photosynthesis. Animal cells and plant cells both contain a nucleus, a cell membrane, a golgi apparatus, ribosomes, mitochondria, smooth and rough endoplasmic reticulum, cytoplasm, and vacuoles. Animal cells also contain lysosomes, which are not usually present in plant cells.

Many of the functions performed by the body are also performed by the cell. Cells produce energy in the mitochondria, generate waste through cellular processes and eliminate this waste with lysosomes. They regulate internal fluids with vacuoles and remain isolated from their environment by way of the cell membrane or wall.

Related terms to know: prokaryote, eukaryote, mitochondria, nucleus, chloroplast

Ecology

Ecology is the study of organisms and their interactions with their environment. This includes small interactions, such as microscopic creatures in their environments, as well as large interactions, such as large mammals and their environmental behaviors. To study for this aspect of the general science test, acquaint yourself with basic ecological functions, ecological systems, and the ways in which ecology is affected by changes in weather patterns, migratory patterns, and the alteration of organisms.

Living Thing Classification

Living things are classified according to a taxonomic structure: domain, kingdom, phylum, class, order, family, genus, and species.

Domains are the least specific and include the largest number of organisms. Kingdoms are more specific than domains and include a smaller number of organisms. Movement from a less specific to more specific taxonomic level shows a greater similarity between organisms within the level.

A mnemonic is useful for remembering the taxonomic structure: “King Philip Came Over For Great Spaghetti,” for example.

Related terms to know: taxonomy