Chapter 3

Question 1

Species heredity (4)

Answer 1

• everyone develops in similar ways at similar ages
• genetic endowment members of a species have in common
• a reason why certain patterns of development and aging are universal
• tied to darwin’s theory

Question 2

Darwin’s theory (3)

Answer 2

• genetic variation in species (they do not all share the same genes)
• some genes aid adaptation more than others do
• natural selection: genes that aid in adaptation to the environment passed on more than those that do not

Question 3

Kettlewell’s study of moths (5)

Answer 3

• a study of pollution and moth color
• light-colored moths survived in rural areas with light-colored trees
• worsening pollution led to darker moth color
• > evolution is not just about genes, development is an interaction of genes and the environment
• an example of cultural evolution: we inherit from previous generations the way we adapt to the environment and passing it down to the next generation

Question 4

The genetic code (5)

Answer 4

• zygote created at conception
• 46 chromosomes/23 pairs, one from father and one from mother
• meiosis: reproductive cell division that splits 46 to 23 chromosomes and produce one egg
• mitosis: cell division
• DNA: double helix comprises each chromosome (20-25k genes)

Question 5

twins

Answer 5

• identical twins (monozygotic): 1 ovum split into 2, genetically identical
• fraternal twins (dizygotic): 2 eggs released and each fertilized by different sperm
• non-identical twins share 50% genes
• child shares about 50% of genes with ea parent
• individuals share some gene with all kin members

Question 6

determination of sex (6)

Answer 6

• 22 of 23 chromosomes (autosomes) similar in males and females
• 23rd pair the sex chromosome
• male has 1 x and 1 y chromosome
• XX the typical genetic code for females
• X has 1100 genes, Y has 80 (many of which are involved in sperm production)
• father’s Y chromosome determines child’s gender

Question 7

mutation (4)

Answer 7

• change in structure or arrangement of one or more genes; produces a new phenotype
• can be inherited (ex. hemophilia - bleed to death)
• environmental hazards (ex. radiation)
• some mutations beneficial

Question 8

chromosome abnormality - down syndrome (3)

Answer 8

• more than 46 chromosomes
• physical: eye folds, short/stubby limbs
• mental: intellectual impact

Question 9

other sex chromosome abnormalities (3)

Answer 9

Turner syndrome: single X chromosome
-physically small, can’t reproduce, spatial/math challenges, stubby fingers

Klinefelter’s syndrome: extra X chromosome
-long limbs, feminine characteristics

Fragile X syndrome: repeated gene sequences

• problem with neuron connections
• intellectual disability, cognitive impairment
• more common in males

Question 10

genetic disease (2, 5)

Answer 10

• 97% of babies born without disease/disorders
• genetic counseling assess potential problems (Cystic fibrosis, hemophilia, PKU, stay sachs)

Sickle cell disease

• sickle-shaped RBC clump and less O2 distributed
• life expectancy 14 years
• die of blood clots, heart/kidney failure
• African Americans have recessive genes/are carriers
• 50% chance having child with sickle cell anemia

Question 11

prenatal screening methods (5)

Answer 11

1. utltrasound - visual image of fetus
2. amniocentesis - sample of amniotic fluid
3. chorionic villus sampling - extract hair cells around fetus
4. maternal blood sampling - blood cells entered mom via placenta
5. preimplantation genetic diagnosis - check DNA of first cells
   - Huntington’s disease single dominant gene
   - strikes mid-life
   - slurred speech, erratic walking
   - irritability, moodiness, dementia, loss of cognitive abilities

Question 12

gene-environmental interplay (5)

Answer 12

• genes turning on/off throughout lifespan
• environmental influences impact from conception to death
• unique genes exert themselves as become adults
• don’t ask how much of genes but rather heredity and environment work together
• genes do not determine anything but rather provide potential