TExES Life Science 7-12 (238) Ultimate Guide and Practice Test2020-05-13T14:46:37+00:00

TExES Life Science 7-12 (238) Ultimate Guide and Practice Test

Preparing to take the TExES Life Science 7-12 exam?

Awesome!

 You’ve found the right page. We will answer every question you have and tell you exactly what you need to study to pass the Life Science 7-12 exam.

TExES Life Science 7-12 (238) Quick Facts

The TExES Life Science 7-12 (238) test evaluates the skills and knowledge required to teach life science in grades 7-12. The questions are based on the Texas Life Science 7-12 framework.

The exam is divided into six domains: Scientific Inquiry and Processes, Cell Structure and Processes, Heredity and Evolution of Life, Diversity of Life, Interdependence of Life and Environmental Systems, and Science Learning, Instruction, and Assessment. It is a computerized test made up of 100 selected-response questions. You are given 15 minutes to familiarize yourself with the computer-administered test (CAT) format and 4 hours and 45 minutes to complete the exam. 

Cost: 

$116

Scoring: 

The score range is 100-300 with a minimum passing score of 240.

Study time: 

Allow plenty of time to review each of the six domains. Also, familiarize yourself with the computer-administered test (CAT) format. Because there are six domains being covered in this test, begin studying several weeks before the scheduled exam so you don’t feel rushed.

Tips that test-takers wish they’d known: 

  • Don’t underestimate the importance of developing a realistic study schedule and sticking to it.
  • Do not leave any answers blank, because your score is based on the number of correct answers. Wrong answers do not count against your score.
  • You cannot bring your cell phone into the testing center, so leave your cell phone and other electronic devices in your car or provided locker.
  • You need to bring two pieces of original identification.

Information and screenshots obtained from the TExES and NES website.

Domain I: Scientific Inquiry and Processes

Overview

Domain I has about 15 selected-response questions. There are three competencies within this domain.

Let’s explore three (of many) specific topics within these competencies.

Precision, Accuracy, and Error

Measurements are accurate when they are close to the correct measurement. Measurements are precise when repeated measurements taken under the same conditions are similar. The precision of measuring tools is very important to both the accuracy and precision of measurements. A precise measuring tool can measure in very small increments. For example, suppose you measure a piece of paper with a ruler whose smallest increment is a tenth of a centimeter and get a measurement of 8.6 cm. You cannot report this as 8.61 cm, because your ruler is only precise enough to measure a tenth of a centimeter. The method of significant figures states that the last number written in a measurement is the first digit with some uncertainty. 

Systems Model

A systems model is a group of related components that can be used to understand and predict behavior in that system. The components of a systems model are input, output, feedback, and processes. Input and output can be either energy or matter. Processes are what change the inputs to outputs. Feedback can be matter, energy, or information, including information that changes the input after flowing from the output. 

When scientists study a system with clear inputs and outputs, they can begin to make predictions about what might happen to outputs when inputs are changed. Systems models are important because they help design and carry out experiments that are difficult or impossible in the real world. Complex systems are difficult to model, so models cannot always include every part of the system. Over time, as scientists understand the parts of the model, they can expand them and make them more complex. Systems can interact with other systems or they can be subsystems of larger systems. 

Scientific Investigations

Scientists use three different types of scientific investigations to research and explain scientific events. 

Descriptive investigations are used when scientists need to describe an organism, natural process, or event. Observations and measurements are taken and carefully recorded. One example of a descriptive investigation is observing cells under a microscope and recording what is seen.

Comparative investigations involve using variables to compare and contrast different organisms, objects, or features. This type of investigation does not include a control group but can include independent and dependent variables. One example of a comparative investigation is comparing seeds sprouted in soil to seeds sprouted in cotton.

Controlled experiments are the most complex type of scientific investigations because they include different variables as well as a control group and experimental group. These investigations only test one variable at a time and the goal is to test the hypothesis. An example of a controlled experiment is testing whether fertilizer makes a plant grow faster. The only variable that is changed is how much fertilizer is added to each plant. Everything else about the plants is kept the same (e.g., the type of pot, amount of light, type of soil, type of plant, type of fertilizer, and type of water).

Domain II: Cell Structure and Processes

Overview

Domain II includes about 20 selected-response questions. There are four competencies within this domain.

Let’s explore just four topics from these competencies.

Carbohydrates

Carbohydrates are macromolecules made up of carbon, hydrogen, and oxygen. There are three varieties of carbohydrates: monosaccharides, disaccharides, and polysaccharides. Monosaccharides, such as glucose, usually contain three to seven carbon atoms and have a formula of (CH2O)n

During a dehydration reaction, two monosaccharides join together to form a disaccharide. A water molecule is released when a hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide. This covalent bond is called glycosidic linkage. Sucrose and lactose are examples of disaccharides.

Long chains of monosaccharides linked by glycosidic bonds are called polysaccharides. Starch, cellulose, and chitin are examples of polysaccharides. Starch is important for energy storage. Other polysaccharides such as cellulose and chitin are important for structure. 

Plant and Animal Cells

Although plant and animal cells are both eukaryotic, they have some differences. Plant cells contain chloroplasts for photosynthesis, but animal cells do not. Plant cells are surrounded by a cell wall and a cell membrane, which help with structure and gives the cell a squared-off look. Animal cells have only a cell membrane. Both types of cells contain vacuoles that are used for waste disposal and storage. Plant cells have a large central vacuole that also helps maintain the structure of the cell, while animal cells have multiple smaller vacuoles. 

Osmosis

During osmosis water moves through a semipermeable membrane from the side of a lower solute concentration to the side with a higher solute concentration. The end result is an equal concentration on each side. Osmosis happens at the membrane surrounding a cell. If the cell contains a higher amount of salt than the surrounding area, water will flow into the cell through the membrane until the concentrations of salt are equal inside and outside of the cell. Osmosis is just one way cells transport water and nutrients across the cell membrane. It allows cells to maintain homeostasis. 

Life Cycle of Viruses

A virus is a packet of DNA or RNA inside a protein shell that reproduces by taking over a host cell. First, a virus must attach to a host cell. It does this through a receptor cell that is on the cell surface. Next, the virus must enter the cell through fusion with the membrane, tricking the cell into absorbing it, or injection. Once the virus has entered the cell, the viral genome is copied and new viral particles are put together. Then the new viral particles leave the cell to infect other cells.

Domain III: Heredity and Evolution of Life

Overview

Domain III has about 20 selected-response questions. There are four competencies within this domain.

Let’s explore four topics from these competencies.

Transcription

Transcription, which is the first step in gene expression, happens when the DNA sequence of a gene is copied into RNA. There are three stages of transcription. 

  1. Initiation: RNA polymerase binds to the promoter, which is a sequence of DNA near the beginning of a gene. Then RNA polymerase separates the DNA strands. Only one strand is needed as a template for transcription.
  2. Elongation: The RNA polymerase reads the template strand and builds an RNA molecule out of complementary nucleotides. This chain grows from 5’ to 3’. This RNA transcript is the same as the DNA strand except that it uses the base uracil (U) instead of thymine (T).
  3. Termination: There are sequences called terminators that signal the end of the RNA transcript. Once the terminators are transcribed, the transcript is released from the RNA polymerase. 

Once termination has finished, the RNA transcript is ready to be translated and it is now called messenger RNA (mRNA). In bacteria, translation can happen right after or even during transcription. But in humans and other eukaryotes, transcription occurs in the nucleus, and translation occurs in the cytosol.

Types of Mutations: Sequence Level

A mutation is a change in DNA. A mutation can change how an organism looks, how it acts, and its physiology. Without mutations, evolution could not happen. Mutations can also cause diseases.

There are three types of mutation: substitution, insertion, and deletion. Substitution occurs when one base is exchanged for another; for example, if the original DNA portion was CTTGAG and after mutation the DNA portion is CTTAAG. Sickle cell anemia is an example of a substitution mutation.

When extra base pairs are inserted into DNA, this is called an insertion mutation, as when the original DNA portion is CTTGAG and after mutation the portion is CTTGGCGAG. 

Deletion mutations occur when a section of DNA is deleted, as when the original DNA portion is CTTGAG and after mutation the portion is CTAG. 

One of the most common causes of mutations is incorrect copying. Another way mutations can occur is exposure to external influences such as chemicals or radiation. These external influences can cause DNA to break down, and when the cell tries to repair the DNA, it does not repair it properly.

Non-Mendelian Inheritance

When Mendel studied pea plants, he found that each characteristic he studied had only two phenotypes. This was because each characteristic was controlled by one gene that had two possible alleles. Scientists are now aware that inheritance is much more complex than this. These more complex inheritance patterns are called non-Mendelian inheritance. 

  • Incomplete dominance happens when the phenotype of a heterozygote offspring is not like the phenotype of either parent. Instead, the phenotype of the offspring incorporates those of both parents. For example, when you cross red snapdragons (SRSR) with white snapdragons (SWSW), the F1 hybrids are all pink (SRSW).
  • Codominance is similar to incomplete dominance. Both alleles are expressed at the same time in the heterozygote. An example is a white flower crossed with a red flower that produces offspring with red and white blotches. 
  • Multiple alleles is a description of more than two alleles for a given gene in a population. One example of this is the C gene, which determines coat color in rabbits. There are four common alleles for this gene: C, cch, ch, and c.
      • CC rabbit: black or brown fur
      • cchcch rabbit: grayish fur
      • chch rabbit: white body and dark ears, face, feet, and tail
      • cc rabbit: solid white coat

Because there are multiple alleles, there are more possible dominance relationships.

  • Extranuclear inheritance most commonly occurs with mitochondria and chloroplasts in eukaryotes. It occurs when genes are transmitted outside the nucleus. One example of this is maternal inheritance. During sexual reproduction, an egg cell with its own nucleus with half the amount of normal DNA and mitochondria meets up with a sperm cell that has its own nucleus with half the amount of normal DNA. They fuse to make a zygote that has the normal amount of DNA. This zygote also has mitochondria from only the egg cell. As the zygote divides and grows, the nucleus replicates and the mitochondria replicate. Because the mitochondria came only from the mother, this is an example of maternal inheritance. 
  • Mosaicism occurs when two different genotypes in an individual came from a single fertilized egg. It happens early on in the development of the embryo. It is caused by an error in cell division that results in some cells with the mutation and others without. An example of mosaicism is the patches of color on a calico cat. 

Hardy-Weinberg Equilibrium

A population that is in Hardy-Weinberg equilibrium is not evolving. This occurs when the alleles in the gamete pool of a population are exactly the same as those of the parent generation.

A population in Hardy-Weinberg equilibrium must meet five assumptions: no mutation, random mating, no gene flow, very large population size, and no natural selection. Populations tend to evolve and are usually not in Hardy-Weinberg equilibrium.

It is possible that a population is in Hardy-Weinberg equilibrium for a single gene, but it is much less likely that the population is in Hardy-Weinberg equilibrium for all of its genes.

Domain IV: Diversity of Life

Overview

Domain IV includes about 20 selected-response questions. There are four competencies within this domain.

Let’s explore four topics from these competencies.

Maintaining Homeostasis

Homeostasis is the internal maintenance of a stable equilibrium despite external changes. For humans to maintain homeostasis, the body must detect changes and counteract them, which usually involves a negative feedback loop. For example, if your body temperature gets too low, a negative feedback loop will help your body raise its temperature. Heat is conserved by constricting blood vessels and shivering, which helps to warm the body.

The hypothalamus plays a large part in maintaining homeostasis in the body. It links the endocrine and nervous systems. Its role is to keep the body in balance and to do this it helps stimulate or inhibit many processes, such as heart rate and blood pressure, body temperature, and appetite and body weight. When the hypothalamus receives a signal from the nervous system, a neurohormone is secreted that will start or stop the secretion of a pituitary hormone. 

One example of how the body maintains homeostasis is when blood sugar levels become too high. The body converts carbohydrates from the food we eat into glucose. When blood sugar levels are high, the pancreas secretes insulin into the body. The insulin binds to the glucose in the blood to allow it to be absorbed and stored as glycogen, lowering the blood sugar. Conversely, when blood sugar levels are too low, the pancreas secretes glucagon. Glucagon breaks down glycogen into glucose in the liver and frees them into the bloodstream. This raises blood sugar levels. 

Important Groups of Bacterial Life

There are many different types of bacteria. Some might seem very unusual in how they have adapted to their environment. Chemosynthetic bacteria have evolved to obtain their energy from inorganic molecules such as ammonia and sulfur. These types of bacteria usually live in remote environments where there is no sunlight, as in the case of bacteria that live in deep-sea vents. Hydrogen sulfide comes out of these vents and the chemosynthetic bacteria are able to oxidize it to sulfur. During this oxidation, they use the chemical energy released to make sugar molecules from carbon, hydrogen, and oxygen. 

Cyanobacteria are bacteria that live in water and photosynthesize. Some are able to live freely while others live in a symbiotic relationship with fungi or plants. This type of bacteria is one of the largest groups of bacteria on earth, thought to be responsible for generating half the world’s oxygen. Cyanobacteria are also the source of chloroplast for plants. At some point during the late Proterozoic or early Cambrian era, cyanobacteria lived inside of certain eukaryotic cells. Eventually, these eukaryotic cells evolved into red algae, green algae, and plants. 

Some bacteria, like Clostridium and Bacillus, are able to form spores called endospores. These spores contain all the genetic material found in the vegetative state of the bacteria, but the spores are dormant. The endospores can stay dormant for years waiting for the right conditions to grow. Scientists have found endospores centuries or thousands of years old. They are extremely resistant to UV radiation, desiccation, high temperatures, and chemicals.

As humans use antibiotics more often, some bacteria are becoming resistant to antibiotics. Staphylococcus aureus is an example of antibiotic-resistant bacteria. It can cause flesh-eating disease and pneumonia. Antibiotic resistance can occur in several ways: antibiotic concentration, bacterial mutation, or bacterial genetic exchange. Antibiotic concentration occurs when there is a biofilm that the bacteria live in. The biofilm is a thick jelly-like substance that an antibiotic cannot penetrate all the way through. The bacteria in the outer parts of the biofilm can be reached by the antibiotic, but the bacteria in the center are exposed to only a portion of antibiotic. 

Bacteria cells replicate very fast and bacteria can evolve much quicker than animals can. Bacterial mutation, such as a change in the cell wall, can sometimes make antibiotics less effective. Bacteria can also share genetic material with each other, even between different species. This is called bacterial genetic exchange. If one species of bacteria has become resistant to antibiotics, it can pass those genes to another type of bacteria. 

Plant Tissues

Vascular plants are made of four types of tissues: dermal, ground, and vascular. 

  1. Dermal tissue is made of cells that cover the outside of the plant. This layer of cells is called the epidermis. A waxy substance called cuticle is secreted from the epidermis cells. Cuticle is a protective layer that prevents water loss in the plant and keeps infections and toxins out. 
    1. Stomata are tiny pores on the underside of leaves that open and close to allow the plant to take in carbon dioxide and release oxygen. 
    2. Root hairs are a type of specialized dermal cell that are long and microscopic. They absorb water and nutrients from the soil. 
  2. Ground tissue is important in metabolism. It provides structural support and can store food and water.
    1. Mesophyll is ground tissue located in leaves. Chloroplasts are found in each mesophyll cell. This is where photosynthesis occurs.
    2. Meristem is found in buds and the tips of roots. The role of the meristem is to start the growth at the tips of roots and shoots and to form buds.
  3. Vascular tissue is made up of xylem and phloem. 
    1. Xylem carries water and minerals throughout the plant.
    2. Phloem carries food throughout the plant.

Tropisms

A tropism occurs when a plant grows toward or away from an external stimulus. Three types of tropisms are geotropism, phototropism, and thigmotropism. 

Geotropism is how plants grow in relation to gravity. Roots growing down is an example of positive geotropism, while shoots growing up are an example of negative geotropism.

Phototropism is the growth of a plant toward or away from light. Positive phototropism is when a plant grows toward light, while negative phototropism is when a plant grows away from light.

Thigmotropism describes a plant moving in reaction to being touched. This is shown in sweet pea tendrils. The tendrils have a tendency to climb, so when they touch something solid they grow toward it. 

Domain V: Interdependence of Life and Environmental Systems

Overview

Domain V has about 15 selected-response questions. There are three competencies within this domain.

Let’s explore three (of many) specific topics within these competencies.

The Carbon Cycle

The carbon cycle is made up of two subcycles. One subcycle deals with carbon exchange among living organisms and the other deals with carbon cycling through geologic processes. These two subcycles are linked by the CO2 pools found in the atmosphere and oceans. Both organisms and geological processes use this pool of CO2.

Carbon in the air exists as CO2. This carbon enters the food web through algae and plants that photosynthesize. These autotrophs convert carbon dioxide into organic molecules. Heterotrophs eat these organic molecules and pass the carbon through the food chains and webs. Cellular respiration breaks down the sugars and releases the carbon into the atmosphere as carbon dioxide. When decomposers break down dead organisms and waste products, they release carbon dioxide into the atmosphere. The carbon cycle within living things can happen very quickly, especially in water.

The geologic carbon cycle can take millions of years because carbon is stored for long periods of time in oceans, soil, and fossil fuels. This stored carbon is brought to the earth’s surface through volcanic eruptions and human use of fossil fuels. Fossil fuels are formed over millions of years as plants decompose in oxygen-free environments. Carbon is released into the atmosphere when humans burn fossil fuels such as gas and oil. Fossil fuels are being used up faster than they can be replenished so they are considered nonrenewable resources. The carbon dioxide released from burning fossil fuels is used by plants and taken up by oceans but not as quickly as fossil fuels are being depleted. The result is an increase in carbon dioxide in the atmosphere, which causes global warming.    

Ecological Relationships

Symbiosis is a long-term relationship between two species that can be positive or negative for either species. 

Parasitism is a type of symbiosis in which one species benefits while the other is harmed. An example of parasitism is a tapeworm living in an animal’s intestine. The tapeworm benefits from having a place to live and food to eat. The animal that it is living in is harmed because the tapeworm takes the animal’s nutrients and can block the intestines.

Commensalism is a long-term relationship in which one species benefits and the other species receives no benefit or harm. An example of this is a tree frog living in a tree. The frog benefits because it receives shelter and protection from the tree while the tree is not harmed, nor does it receive a benefit from the frog.

Mutualism is a long-term relationship in which both species benefit. One example of mutualism is the relationship between an oxpecker and a rhinoceros. The oxpecker eats ticks off the back of the rhino, gaining food. The rhino benefits because it gets the parasite removed from its back. 

Population Density Factors

Population density is the number of individuals in a population per unit of area. There are three different ways organisms can be distributed: clumped, random, or uniform. Clumped dispersion occurs when organisms are clustered in smaller groups. Animals that live in herds or schools, such as bison or fish, show this type of dispersion. Plants that drop their seeds underneath them, like oak trees, will also show clumped dispersion.

Random dispersion occurs when there is no pattern to how the organism is dispersed. This is seen in plants that require wind to disperse their seeds. The seeds will grow when they land in an optimal environment, wherever that happens to be.

Uniform dispersion is when organisms are spaced fairly evenly throughout the population. An example of this is a population of nesting penguins that aggressively protect their territory. 

Domain VI: Science Learning, Instruction and Assessment

Overview

Domain VI has about 10 selected-response questions. There are two competencies within this domain.

Let’s explore two (of many) specific topics within these competencies.

ELL Students

It is important for teachers to adjust their curriculum to assist English language learners (ELL). Science classes require students to learn a lot of new vocabulary, which can be challenging even for English speakers. Science teachers should have a few strategies available to them to make science vocabulary more attainable to ELL students.

Listed below are a few examples of ways to assist ELL students in science class.

  • Allow students to work in groups.
  • Use nonverbal cues and slow down when you’re talking.
  • Use images as much as possible.
  • Learn about the students’ cultures and incorporate what you learn into their learning.
  • Give ELL students vocabulary lists and study guides.
  • Have students keep a vocabulary journal with definitions and images.
  • Use visual aids such as graphs and charts to help ELL students with concepts.
  • Stick to a classroom routine.
  • Pause frequently when showing videos to check for questions.

Assessment

It is important to use a variety of assessments when checking students’ progress. 

Performing a diagnostic assessment before starting a lesson is a great way to determine what the students already know about a topic. This type of assessment will also make a student’s strengths and weaknesses clear.

Formative assessments are a way to check in with the students during the lesson. This type of assessment will give you information about which students might need more individualized support.

Summative assessment occurs at the end of a lesson. This will give you feedback on what parts of the instruction went well and what didn’t.

In performance assessments, students can apply their knowledge and skills to a real problem. The students’ end product, such as a report or experiment, should be scored using specific criteria.

Self-assessment is a valuable tool to teach students how to be self-reflective. Students evaluate their own work to determine their strengths and weaknesses and where they need to focus their attention. Self-assessment can be used in conjunction with peer assessment.

Peer assessment is not only valuable to the student being assessed, but also to the student doing the assessing. It allows the assessor to develop confidence in their skills and knowledge, especially if they are required to give feedback.

And that’s some basic information about the test.

Not Sure Where to Start?

Let us help.

Simply fill out the contact form and we
will get in touch within 1 business day.

Our First Customer

A very personal story from our Founder Scott Rozell and his wife, Lacey.

50,000 Have Used 240 Tutoring to Pass
Their Exams Since 2017.

Are you ready to join them?

Select to Login