Fig. 10-1a, p.152
Fig. 10-1b, p.152
ATP ATP
p.153
Fig. 10-2, p.154
a Garden pea flower, cut in half. Sperm form in pollen grains, which originate in male floral parts (stamens). Eggs develop, fertilization takes place, and seeds mature in female floral parts (carpels).
b Pollen from a plant that breeds true for purple flowers is brushed onto a floral bud of a plant that breeds true for white flowers. The white flower had its stamens snipped off. This is one way to assure cross-fertilization of plants.
c Later, seeds develop inside pods of the cross-fertilized plant. An embryo within each seed develops into a mature pea plant.
d Each new plant’s flower color is indirect but observable evidence that hereditary material has been transmitted from the parent plants.
Fig. 10-3, p.154
carpel stamen
b A gene locus (plural, loci), the location for a specific gene on a chromosome. Alleles are at corresponding loci on a pair of homologous chromosomes
d Three pairs of genes (at three loci on this pair of homologous chromosomes); same thing as three pairs of alleles.
Fig. 10-4, p.155
a A pair of homologous chromosomes,both unduplicated. In most species, oneis inherited from a female parent and itspartner from a male parent.
c A pair of alleles may be identicalor not. Alleles are represented in the text by letters such as D or d.
fertilization produces heterozygous offspring
meiosis II
meiosis I
(chromosomes duplicated
before meiosis)
Homozygous dominant parent
Homozygous recessive parent
(gametes) (gametes)
Fig. 10-5, p.156
Trait Studied
Dominant Form
Recessive Form
F2 Dominant-to-Recessive
Ratio
Seed shape
Seed color
Pod shape
Pod color
Flower color
Flower position
Stem length
2.98:1
3.01:1
2.95:1
2.82:1
3.15:1
3.14:1
2.84:1787 tall 277 dwarf
651 long stem 207 at tip
705 purple 224 white
152 yellow428 green
299 wrinkled882 inflated
6,022 yellow 2,001 green
5,474 round 1,850 wrinkled
Fig. 10-6, p.156
female gametes
mal
e g
amet
es
Fig. 10-7a, p.157
a From left to right, step-by-step construction of a Punnett square. Circlessignify gametes. A stands for a dominant allele and a for a recessive allele atthe same gene locus. Offspring genotypes are indicated inside the squares.
A
A A A A
AAAAA
Aa
AaAa
AaAaaa aa aa aa
a
a
a
a
a
a
a
a
Fig. 10-7b, p.157
A
AA
Aaa Aa
AaAa
A
a
aa
Aa Aa
AaAa
True-breeding homozygousrecessive parent plant
F1 offspring
b Cross between two plants that breed true for different forms of a trait.
True-breeding homozygousdominant parent plant
Fig. 10-7c, p.157
AAa
AAa
Aa
a
a
Aa
AA Aa
aaAa
F2 offspring
HeterozygousF1 offspring
HeterozygousF1 offspring
c Cross between heterozygous F1 offspring.
aa
AA
p.165
the expectedphenotypicratio of 3:1
(dominant)(dominant)(dominant)(recessive)
AA AAAaAaaa
aa
Aa
Aa
A
A
a
a
Fig. 10-9, p.159
parent homozygous recessivefor white flowers, short stemsGametes at fertilization
parent homozygous dominantfor purple flowers, tall stems
Meiosis, gamete formationin true-breeding parent
plants
Possible genotypes resulting from a cross between two F1 plants:meiosis,gameteformation
All F1 plants are AaBbheterozygotes with purpleflowers and tall stems.
meiosis,gameteformation
Fig. 10-10, p.160
Phenotypes(Blood type):
Genotypes:
A AB B O
or
ABAO BO OO
BBAAor
Fig. 10-11, p.160
Cross two of theF1 plants, andthe F2 offspringwill show threephenotypes ina 1:2:1 ratio:
homozygousparent (RR)
homozygousparent (rr)
heterozygousF1 offspring (Rr)x
RR Rr Rr rr
Fig. 10-13, p.161
EB Eb eB eb
EB
Eb
eB
eb EeBbblack
EeBBblack
EEBbblack
EEBBblack
EEBbblack
EeBBblack
EeBbblack
Eebbchocolate
EeBbblack
EEbbchocolate
EeBbblack
Eebbchocolate
eeBByellow
eeBbyellow
eebbyellow
eeBbyellow
Fig. 10-16, p.163
p.164
Fig. 10-19a, p.164
Range of values for the trait
This red graph line of therange of variation for a traitin a population plots out asa bell-shaped curve. Suchcurves indicate continuousvariation in a population.
Nu
mb
er
of
ind
ivid
ual
sw
ith
a m
eas
ura
ble
val
ue
fo
r th
e t
rait
Fig. 10-19c, p.164
Fig. 10-20a-b, p.166