Chapter 2 Flashcards & Key Terms

adaptive
Helping the propagation of an organism’s genes.
asexual reproduction
Reproduction in which all the offspring’s genes are inherited from a single parent.
autosome
Any chromosome other than a sex chromosome.
chromosome
A rod-shaped nuclear organelle composed of DNA and associated proteins.
clitoris
The erectile organ in females, whose external portion is located at the junction of the labia minora, just in front of the vestibule.
conjugation
Contact between two bacteria accompanied by the transfer of a short stretch of DNA from one to the other.
copulation
Sexual intercourse, or coitus.
courtship behavior
Behavior that attracts a mate.
diploid
Possessing the full complement of chromosomes.
DNA (deoxyribonucleic acid)
The linear molecule that forms the chemical basis of genes in all species except some viruses.
estrus
The restricted period within the ovarian cycle when females of some species are sexually receptive; “heat.”
eukaryote
An organism whose cells contain nuclei.
evolution
The change in the genetic makeup of living populations over time.
fluctuating asymmetry
A difference between the left and right sides of the body that results from random perturbations of development.
gamete
A germ cell (ovum or sperm) that fuses with another to form a new organism.
gene
A stretch of DNA that is transcribed as a functional unit; a unit of inheritance.
genome
An organism’s entire complement of DNA, including all its genes. In some viruses, such as HIV, the genome is composed of RNA.
gestation
Bearing young in the uterus; pregnancy.
gonad
An organ that produces gametes (a testis in males; an ovary in females).
haploid
Possessing half the usual complement of chromosomes.
heritable
Capable of being passed down from parent to offspring.
hermaphrodite
An organism that combines male and female reproductive functions.
inclusive fitness
The likelihood that an individual’s genes will be represented in future generations, both in direct descendants and in the descendants of close relatives.
internal fertilization
Fertilization within the body.
investment
The commitment or expenditure of resources for a goal, such as reproductive success.
kin selection
The theory that it can be advantageous, in evolutionary terms, to support the reproductive success of close relatives.
lactation
The production of milk in the mammary glands.
mate guarding
A behavior in which a male animal prevents sexual contact between his mate and other males.
meiosis
A pair of cell divisions that produces haploid gametes.
mitosis
Cell division in which the chromosome number is preserved.
monogamy
1. Marriage limited to two persons. 2. A sexual relationship in which neither partner has sexual contact with a third party.
mutation
A change in an organism’s genome.
natural selection
The survival and reproduction of those individuals that are best adapted to their environment.
ovum (pl. ova)
A mature female gamete, prior to or immediately after fertilization.
pair bond
A durable sexual relationship between two individuals.
parthenogenesis
Asexual reproduction from an unfertilized ovum; “virgin birth.”
paternity test
A test to identify an individual’s father by DNA analysis.
pheromone
A volatile compound that is released by one organism and that triggers a specific behavior in another member of the same species.
polyandry
The marriage or mating of one female with more than one male.
polygamy
Marriage to or (mostly in animals) mating with more than one partner.
polygyny
The marriage or mating of one male with more than one female.
polymorphism
A common genetic variation between individuals in a species.
proceptive behavior
Behavior by females that may elicit sexual advances by males.
promiscuity
Engaging in numerous casual or short-lived sexual relationships.
Red Queen hypothesis
The idea that sexual reproduction is advantageous because it helps defend organisms against parasites.
scrotum
The sac behind the penis that contains the testicles.
semen
The fluid, containing sperm and a variety of chemical compounds, that is discharged from the penis (ejaculated) at the male sexual climax.
sex chromosome
Either of a pair of chromosomes (X or Y in mammals) that differ between the sexes.
sex determination
The biological mechanism that determines whether an organism will develop as a male or a female.
sexual monogamy
A sexually exclusive pair bond.
sexual reproduction
Reproduction in which the offspring inherit genes from two parents.
sexual selection
The evolution of traits under the pressure of competition for mates or of choice by mates.
social monogamy
A pair bond that is not sexually exclusive.
sperm
A male gamete, produced in the testis.
SRY (Sex-determining Region of the Y chromosome)
A gene located on the Y chromosome that causes the embryo to develop as a male.
vulva
The female external genitalia.
X chromosome
A sex chromosome that is present as two copies in females and one copy in males.
Y chromosomes
A sex chromosome that is present only in males.
zygote
A cell formed by the fusion of gametes: a fertilized ovum.
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