This document contains instructions and questions for a biology exam consisting of two papers. Paper I contains 20 multiple choice questions testing core genetics concepts such as Mendelian inheritance, meiosis, mitosis, non-disjunction, and Down syndrome. Paper II contains longer, open-response questions involving applying genetics concepts like setting up punnett squares and interpreting pedigrees related to conditions like hemophilia. The exam is scheduled for Friday, December 9th, 2011 and students are instructed to show all work, use pen only, and write clearly.

1. UNDECIMO NACIONAL Name Student:
Biology
Paper I & II
1 1/2 hour
Friday 09 December 2011
INSTRUCTIONS TO CANDIDATES
Do not open this examination paper until instructed to do so.
Answer all the questions.
For each question, choose the answer you consider to be the best and indicate your choice
Answer all in the spaces provided.
Use pen only
Use clear handwriting
Paper I
Puntos Nota
20-20 7
19-17 6
16-14 5
13-12 4
11-8 3
7-4 2
3-1 1
Paper II
Puntos Nota
20-20 7
19-17 6
16-14 5
13-12 4
11-8 3
7-4 2
3-1 1
Paper I
1. Having two different alleles for a trait; hybrid
EJE 1
Evaluación Semestral II Periodo Núcleo Genética Teórica

2. a. Heterozygous
b. Homozygous
c. Phenotype
d. Genotype
2. Mendel's name for a specific trait that appeared in the F1 generation
a. Hybrid
b. Homozygous
c. Genotype
d. Dominant
3. Mendelian law that states a random distribution of alleles occurs during the formation of
gametes
a. Genetics
b. Dominant
c. Lawof segregation
d. Law of independent assortment
4. The condition in which an organism has extra sets of chromosomes
a. Polyploidy
b. Hybrid
c. Recessive
d. Allele
5. New combinations of genes produced by meiosis & fertilization
a. Fertilization
b. Law of segregation
c. Genotype
d. Geneticrecombination
6. Random distribution of alleles that occurs during gamete formation
a. Crossingover
b. Dominant
c. Law of segregation
d. Law of independentassortment
7. A double set of chromosomes
a. Trait
b. Hybrid
c. Diploid
d. Haploid
8. Genetic information passing from one generation to the next through reproduction
a. Trait
b. Recessive
EJE 2
Evaluación Semestral II Periodo Núcleo Genética Teórica

3. c. Heredity
d. Gene
9. A single set of chromosomes
a. Hybrid
b. Diploid
c. Haploid
d. Allele
10. An organism's genetic makeup, or allele combinations
a. Genotype
b. Gene
c. Phenotype
d. Allele
11. When the two alleles of a pair are different, one can be dominant and the other recessive,
dominant will mask recessive
a. Lawof segregation
b. Homozygous
c. Lawof dominance
d. Dominant
12. First law of heredity stating that pairs of alleles for a trait separate when gametes (sperm or egg)
are formed
a. Lawof segregation
b. Lawof dominance
c. Genotype
d. Allele
13.
EJE 3
Evaluación Semestral II Periodo Núcleo Genética Teórica

4. a. Show punnett square and genotype ratios for cross Aa x Aa
b. In pea plants, the allele for yellow (Y) is dominant and green (y) is recessive, and the allele
for round is (R) and wrinkled is (r). Cross a heterozygous yellow, heterozygous round pea
plant with a heterozygous yellow, heterozygous round plant. What are thephenotypes of
theoffspring?
c. In pea plants, the allele for yellow (Y) is dominant and green (y) is recessive. Cross a
Heterozygous yellow pea plant with a homozygous green plant. What are thegenotypes and
phenotypes of theoffspring?
d. Lawof dominance
14. Name of the two new cells produced during Mitosis.
a. Interphase
b. DaughterCells
c. Sex cells
d. Bodycells
15. First phase when the chromosomes make identical copies of themselves.
a. Anaphase
b. Interphase
c. Telophase
d. Metaphase
16. Second phase when Mitosis begins and the poles and spindle fibers appear.
a. Telophase
b. Prophase
c. Anaphase
d. Metaphase
17. The process that produces four different sex cells.
a. Meiosis
b. Metaphase
c. Mitosis
d. Telophase
18. - Variable proportions of cells in the body are of normal karyotype/downs karyotype
-occurs as a result of non-disjunction in the zygote
-phenotypically the child has a milder form of the condition
- Affects approx 1% of downs syndrome children
EJE 4
Evaluación Semestral II Periodo Núcleo Genética Teórica

5. a. Describe the clinical features of downs syndrome
b. What is the genetic abnormality in Down's syndrome?
c. What is mosaicism and what proportion of downs syndrome children have this?
d. What Ultrasound finding may be suggestive of Downs syndrome in utero?
19. Non-dysjunction
- error of meiosis
- one pair of chromosome 21 fails to separate
--> one gamete has two 21s and one has none
-80% of times this is in the female -->incrassoc of downs with maternal age
a. What other mechanisms can give rise to trisomy 21?
b. What is the commonest mechanism for trisomy 21?
c. What is the genetic abnormality in Down's syndrome?
d. Describe the clinical features of downs syndrome
20. Mild to moderate intellectual disabilities, low muscle tone, upward slant to the eyes, flat facial
profile, enlarged tongue
a. What detects down syndrome in fetuses 70% accurarately?
b. When does down syndrome occur?
c. What characteristics would someone with down syndrome present with?
d. Why are more down syndrome born to women under the age of 35?
Paper II
1.Mendel is known as the father of genetics for his extensive experimental work with peas and
different types of crosses.
EJE 5
Evaluación Semestral II Periodo Núcleo Genética Teórica

6. a. Complete the punnet grid below to show the outcome of the monohybrid cross [5]
a. Complete the punnet grid below to show the possible outcomes of a cross between two
members of the F1 generation. Describe all genotypes produced.
[5]
2. Hemophilia is a blood-clotting disorder that is also recessive and sex-linked.
EJE 6
Evaluación Semestral II Periodo Núcleo Genética Teórica

7. a. State the normal function of the gene associated with hemophilia. [2]
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
……………………………………………………………………………………………..
b. Describe the effects and symptoms of hemophilia. [1]
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
……………………………………………………………………………………………..
c. Use the pedigree chart to deduce the possible genotype(s) of the named individuals. [7]
Leopold
Helen
Alice
Mary
Rubert
Bob
Britney
¡Enjoy the science!
EJE 7
Evaluación Semestral II Periodo Núcleo Genética Teórica