SNow Day Wednesday!
Genetics Test on Thursday.
Prep for test using your study guide:

7^th Grade Genetics Study Guide (Answered)

Mr.  Goldsmith

Instructions: Prepare for our Genetics test: answer these questions using your 1) mind; 2) notebook, 3) online book to which you can Link from my Blog or by typing in this web address: http://www.beasleyac.org/ourpages/auto/2013/9/16/50402231/IAES%202nd%20Edition%207th%20Grade.pdf  or 4) the web:

1.    What is the definition of genetics? The study of______________________________

Ans) Genetics - location and behavior of genes, their passage to offspring, and of how characteristics are inherited.

2. How are traits related to characteristics?

Ans) Traits are the different versions of a characteristic. Ex: Eye color is a characteristic, and traits include blue eyes, green eyes, and brown eyes.

3. Which of the following traits can be inherited?
1. Hand tattoo
2. Hitchhiker’s thumb
3. Being bilingual (speaking two languages)
4. Plays soccer

Ans) b

4. Can a trait be determined by one gene?________ By several genes?_____ 

Ans) Yes to both. Some traits are determined by one gene, and some are determined by several genes.

5. Can traits be determined or affected by the environment? _yes  Give examples:

1. Hair and skin color can be affected by exposure to sunlight

2. _injury (ex: amputation) or disease (ex: amputation; diseases such as pellagra, cancer, leprosy)
3. Lack of resources like food or space can lead to decreased growth.  Ex: malnutrition, picky eaters, island dwarfism.

6. Where are chromosomes located?  In the _____________ of each cell. 

             nucleus

7. How many pairs of chromosomes do humans have in their cells? _____

     23 pairs

8. How many chromosomes do humans have in their cells? _____

           46

9. How many chromosomes do humans get from their parents?                                                      .                     (23 from each parent)

10. Where are genes located?

              On the chromosomes

11. What does it mean to say that a gene or trait is “dominant”?

A dominant trait is that version of a gene that shows with only 1 copy of an allele, or version of a gene. Always shown with a capital letter.

12. How would you symbolize the dominant gene for Purple flowers on a pea plant?

With a capital P.

13. What letter would you use to symbolize the gene for White pea flowers (recessive)?

With a lower-case “p”.

14. What is a “recessive” gene?

A version of a gene that is hidden if combined with a dominant trait; a genetic trait that is not shown in an heterozygous individual.

15. Using the letter ‘N, show the following genotypes:
1. Homozygous dominant: NN
2. Heterozygous:  Nn or nN
3. Homozygous recessive: nn

16. Complete a Punnett square for two Sea Stars that are heterozygous for pink skin.  This information will be used for the next two questions as well.

NOTE: P stands for pink skin, while p stands for purple skin.

17. Using the information from the Punnett Square above, what percent of the offspring are likely to have pink skin, on average?  Show all necessary work.  

             75%

18.  Using the information from the Punnett Square above, what percent of the offspring are likely to have purple  skin, on average?  Show all necessary work.

            25%

19. How is the term “homozygous” different from the term “heterozygous”?

Homozygous organisms have 1 type of allele for a characteristic (both alleles are the same), while heterozygous organisms have 2 kinds of alleles for a characteristic (two different alleles).

.

20. Make a Punnett Square to show the probability of heterozygous green seed to homozygous yellow seed offspring. For this question, Green seed is dominant, and yellow seed is recessive.

21. Show the fraction and percentage of green seeds and yellow seeds for the cross shown in the Punnett Square, above.
22. ----------------------

        l                               l
        l-----------------------l

        l                               l
        l-----------------------l

•  
• green seeds fraction: ½  percentage: 50% 
• yellow seeds : ½,   percentage: 50%

22. What are some differences between Sexual reproduction and Asexual reproduction?
1. Number of parents                    ______2_______         ______1________
2. Compare parents to offspring  _different_____            ____same________
3. Cell types taking part                ___2_________         _____1___________
4. Number of steps                       _Mitosis 4_     _           _Meiosis  8_______
5. Include Clone, Budding                                                                                           or runners                                 _______  _____           ________X________
6. Involve gametes                       _____X_________         ________________
7. Which organisms reproduce in each way ( answer next parts with yes or no)

1) Can humans?                   ___yes_____          ______no______

         2) Can plants?                      ___ yes ______        ____ yes ______

                    3)  Can bacteria and amoebas ?    ____ no ______         __ yes ________

23. Label each of the following by filling in the blank with either Sexual Reproduction (SR) or Asexual Reproduction (AR):
1. Red flowered plant and white flowered plant produce offspring with pink flowers SR
2. Lizard sperm unites with Lizard egg SR
3. Yeast cell makes a copy of itself AR
4. A Red Delicious apple seed is crossed with Granny Smith (green) apple pollen to make a Red Smith apple tree seed._ SR _
5. Offspring Gets genetic material from one parent __ AR___
6. Offspring can never be an identical copy of parent or sibling _ SR __

24. Mutations are always harmful:  True or False? (circle one)  Explain your answer:               False: _Some mutations are helpful, and some have no effect. It said this in our textbook.

25. To study human genetics, do we use:

a)    breeding organisms other than humans

b)   breeding humans

c)    studying human pedigrees, or records of their ancestry

d)   examining human DNA

(You can circle more than one of the above)

Answer: Circle a, c, and d.

26. In nature, can an offspring ever be an exact copy of one of its parents or siblings (OTHER than an identical twin)?  Explain why or why not: _

__Yes, where an organism uses asexual reproduction. the offspring gets all of its genes from one parent, which makes it a clone of the parent.

27. Based on your answer to the previous question, do you agree that each human (other than identical twins) is genetically unique?

In sexual reproduction. the offspring gets its genes from two parents. Every trait where the parents differ is decided by which genes were passed in the gametes, and which traits are dominant. This makes the offspring unique from either parent.

28. Where is DNA usually located?

In the nucleus, coiled up in the chromosomes.

29. What is a carrier (in genetics)?

An organism that is heterozygous for a recessive genetic condition, and is unaffected by it, but can pass the gene along to its offspring.

30.  If 2 parents are both carriers for a recessive genetic trait, then their offspring have what chance of getting (inheriting the trait):

a.    0%

b.   25%

3. 50%
4. 100%

31. What is a pedigree?

A family tree about a single trait.

32. For the trait show in the pedigree to the right, label each circle and square as D (Dominant) or d (recessive) for the trait:

• DD         dd Dd   Dd   Dd   Dd        DD   Dd   Dd    dd

  Shaded square and circle are homozygous recessive.
• Mated circle and square in the 2^nd Generation are both heterozygous recessive.
• No one in 2^nd generation is homozygous recessive, so 1^st generation square was probably Homozygous dominant.
• 2^nd generation cross with 2 heterozygous recessive means all 4 2^nd generation offspring are heterozygous recessive.
• 3^rd generation has  3:1 phenotype ratio, so expect 1 is DD and two are heterozygous recessive.

33. Use the following pedigree. Note that Type A blood is the dominant trait in this pedigree.  What are Joseph’s blood type alleles?

a.    AA

2. AO
3. OO
4. Either AA or AO

34.  Which blood type is dominant (from each pair, circle one):     A or O       B or O        AB or O

35. Why is this a trick question:  Which blood type is dominant (circle one of this pair):      A or B    

It’s a trick question because A and B are co-dominant.

36. What are the names of the male and female gametes (sex cells)?  sperm  and egg_.

37. What is fertilization? 

Union of sperm and egg into a zygote, or a new organism. 

38. How are meanings of the terms similar and/or different?

39. One of your friends says that arm strength is mostly inherited from your parents and grandparents and you can't do anything about it.  Another friend says that it is caused by environmental factors that you can control.  What do you think?  Explain your answer.  

I’d say that a possible range of arm strength is determined by genes inherited from your parents, but that you can improve arm strength within that range by exercising your arm and other muscles with weights or through heavy physical work

40. Nature vs. nurture - Scientists often argued about whether an organism’s traits are caused by the world around them (ex: strong from lots of exercise) or because of the genes they inherited from their parents (muscular build or not).  Of course, very few people have ideal strength, or truly great strength in every part of their body. Everyone’s strength is different from one another’s. These differences are referred to as talents. So scientists are doing a study to see how people differ from the ideal.  It will take years to identify the advantages and disadvantages of each of the various body parts’ strengths.  The short-term goal of the project is to find the physical strength problems a person is likely to encounter during his or her lifetime.  The long-term goal is to have each person live a stronger, healthier life.

1. Is a person’s body strength caused by genes or environment? 

Available range is probably caused by genes, but can be improved with environmental factors, like exercise.

2. Can a child of physically weak parents grow stronger, however, because the child got better nutrition or exercise than the parents, or because the parents were exposed to disease or toxins that the child avoided?

                     Yes, the child  should be able  to  improve his or her strength.

3. What are the short term goals of the study?

The short-term goal of the project is to find the physical strength problems a person is likely to encounter during his or her lifetime

4. What are the long term goals of the study?

  The long-term goal is to have each person live a stronger, healthier life.

5. What does the author mean when they discuss talent?

                        Differences in everyone’s strength from one another’s.

6. Why would they want to find differences from the ideal strength?

                        To identify the advantages and disadvantages of each of the various body parts’ strengths.