Humans have thousands of genes that combine in different ways to help create unique individuals. Where is the genetic code primarily located?

Curly hair and the ability to taste the chemical PTC are inherited traits. Curly hair (H) is always dominant to straight hair (h). The ability to taste PTC (P) is always dominant to not being able to taste PTC (p). The alleles for straight hair and a non-taster for PTC are recessive. 

If both parents are heterozygous for both traits, what would the genotype of an offspring with straight hair and the ability to taste PTC?

Scientists have reported that more than 95% of the factors that lead to some types of cancer are caused by random DNA-copying errors. During which phase of the cell cycle do these DNA-copying errors most likely occur?

Nitrogen is an essential component of all living things. However, atmospheric nitrogen is unavailable for organisms to use. Through various processes and chemical changes, nitrogen moves through the biosphere, atmosphere, and geosphere in different forms, making it available for all organisms. Atmospheric nitrogen is deposited in the soil and surface waters primarily through precipitation. Once in the soil, microorganisms break down the nitrogen into different forms, which is taken up by plants. Nitrogen eventually makes its way back into the atmosphere. 

What would happen within the nitrogen cycle if  a bactericide, a substance that kills bacteria, was added to the soil?

A student claims that the influenza virus replicates in the air and then infects people. Which statement BEST describes the claim?

A DNA mutation results in a protein that is the same as the initial protein synthesized before the mutation. Which statement BEST explains this outcome?

Giant salvinia is a floating fern native to Brazil introduced to Texas as an aquarium plant and is now found in large bodies of water across the state. The invasive plant by be carried to new bodies of water by fishing and recreational boats. It grows quickly, covering large areas of the water's surface. When the plant dies and decomposes, the oxygen content in the water declines. 

Which statement BEST describes how  giant salvinia affects a Texas ecosystem and provides the correct evidence?

Milk that is sold for human consumption is often pasteurized. During this process, the milk is heated to a high temperature. Which statement describes the main benefit of this process?  

Scientists can use the fossil record to determine changes in an environment. What does the abrupt appearance of new organisms show? 

The abrupt appearance of new organisms is evidence of ______________ and ________________. 

A scientist examined two populations of the grasshopper species Atractomorpha lata. The scientist found that the population raised in higher temperatures had a higher frequency of brown coloration, while the population raised in lower temperatures has a higher frequency of green coloration. 

Based on this information, which biological process is affected by temperature in A. lata?

A student is making a table to describe the processes of photosynthesis and cellular respiration. Complete the table by identifying which process causes each result shown in the table. 

Which statement accurately compares eukaryotic cells and prokaryotic cells?

A student observed a human cheek cell under a light microscope and made these observation: 

- The chromatin is condensed. 

- There is no visible nucleolus. 

- The spindle fibers are visible. 

- The nuclear membrane looks like it is disappearing. 

Which phase of the cell cycle is the student MOST LIKELY observing?

Cystic fibrosis is an autosomal recessive disorder in humans. What is the probability that an offspring will have cystic fibrosis if both parents are carriers of cystic fibrosis? 

As part of a wildlife conservation program, researchers take a small population of wolves and relocate them to an island. After several generations, researchers analyze the genomes of the wolves in the population and determine there is little genetic variation in the population. 

Which evolutionary mechanism BEST explains the low level of genetic variation of these wolves?

Which table correctly identifies organelles found in plant cells and in animal cells?

Giraffes (Giraffa camelopardalis) have 30 chromosomes in their somatic cells. How many chromosomes will each daughter cell have after the final step of meiosis? 

The oak mistletoe is a green, leafy plant that grows on trees and has white berries. Mistletoe seeds are spread to other trees through the waste of birds that feed on the berries. The mistletoe seedlings grown into the tree to obtain water and nutrients. 

Which answer choice correctly identifies a relationship between two of these organisms?