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Bacteria use restriction enzymes and Cas9 enzymes that target specific sequences of DNA to defend themselves against which of the following selfish genetic elements?

The statement that racial categories are social constructs, and have no basis in biology is, in part, predicated on observations of human genetic diversity.  Which of the following statements best describes the distribution of genetic variation among racial groups? 

Restriction enzymes and the Cas9 enzyme are two mechanisms bacteria use to fight viruses.  What characteristics of these enzymes defend bacteria against viruses, but also make them such useful tools for genetic engineers?

This phylogenetic tree depicts the evolutionary relationships of eight major vertebrate classes.  Tiktaalik is an intermediate fossil that represents an early ancestor of tetrapods (four-limbed animals) and the transition from water to shoreline. If you were to add Tiktaalik to this phylogeny, where would the Tiktaalik branch extend from?

Processes in the thalamus are involved in cognitive judgments about pain, which contributes to the strong emotions often experienced during pain.

Nociceptors in the peripheral nerves first sense injury and, in response, release chemical messengers, which are conducted to the spinal cord.

Fill in the missing words (8 marks)    Allergies  Allergies are the most widespread immune problem. They are a signal that the immune system is [9-11] by mistake. Most allergic reactions generally make the majority of people [12]. They are common and usually not very [13].    Correctly spell the word for a more serious allergic reaction that affects the whole body:  [14] reaction    To prevent allergies, the immune system can be built up by introducing small [15] of the allergen to the body to make us less [16] to them and to not to react too strongly. 

What is another word for ‘deficient’?

Another way to say ‘resist’ a disease is:

What can overpower the short term pleasure of distractions?