multiple choice Flashcards
what is life cycle?
generation-to-generation sequence of stages in the reproductive history of an organism.
how does offspring acquire genes from parents?
by inheriting chromosomes
inheritence is possible because of:
-dna replication
-fertilization
what is asexual reproduction?
offspring are genetically identical to parent (no variation)
what kind of cell division is asexual reproduction?
mitotic cell division
what is sexual reproduction?
production of offspring by combining chromosomes from two different parents (sperm + ovule = zygote)
what is dna replication?
copying of dna that happens during interphase
how many chromosome pair does human has?
46
each parent contributes how many chromosomes?
23
what is homologous chromosome?
one of two paired chromosomes, one from each parent
is gametes diploid or haploid?
haploid
what is sex cells or gametes?
haploid that contains one copy of each chromosome (sperm + egg)
what are the same characteristics that each pair of homologous chromosomes has?
-same length
-same centromere position
-position of genes
what is the difference between each pair of homologous chromosomes?
they might not code for the exact same type of body part/not code for exact version of each gene.
what iis homologous pairs?
matching pairs of chromosomes in a diploid cell that both code the same traits.
what does meiosis do to the number of chromosomes from diploid to haploid?
reduces
what type of cellular reproduction is meiosis?
eukaryotic
what is meiosis?
eukaryotic cellualr reproductiion in which the cells produced have half the number of chromosomes of the parent cell.
what are the two main phases of meiosis?what happens in those phases?
-meiosis i (homologous pair separate)
-meiosis ii (sister chromatids of each chromosome separate
what does the organism produces to maintain the same number of chromosomes from generation to generation?
gametes
how many chromosomes does human gametes contains?
23
cell with n chromosomes is called…
haploid
a cell that contains 2n chromosomes is called…
diploid
how many set of chromosomes does haploid has?
one
in humans, 2n is equal to how many chromosomes?
46
meiosis is involve in…
sexual life cycles in animals
what does meiosis produces?
gametes
when gametes combine in ______, the number of chromosomes is _____.
fertilization;restored
this involves two consecutive cell divisions called ___ and ___. (sexual reproduction: 2N->N (gametes) )
stages of meiosis;meiosis i and meiosis ii
what happens in interphase?
-chromosomes replicate
-chromatin condenses
what happen during prophase i?
pairing of homologous chromosomes occurs
in prophase i, how many chromatids does each chromosomes consist?
two
in prophase i, what happens to the nuclear envelope?
breaks down
what forms during prophase i?
spindles
what happens DURING prophase i?
crossing over produces exchange of genetic information.
what is crossing over?
chromosal segments are exchanged between a pair of homologous chromosomes.
what happens in metaphase i?
homologous chromosomes line up at the equator.
_______ _____ attach to spindle fibers.
chromosome centromeres
in anaphase i, what happens to homologous chromosomes?
they separate and move to opposite poles of the cell.
what happens to the cell in telophase i?
cell divides
what happens to spindles in telophase i? what happens to chromosomes?
-breaks down
-chromosomes uncoil and form two nuclei
what happens in prophase ii?
-second set pf phases begins
-spindles apparatus foorms and the chromosomes condense.
what happens during metaphase ii?
haploid number of chromosomes line up at the equator.
what happens during anaphase ii?
-sister chromatids are pulled apart at the centromere by spindle fibers and move toward to opposite poles of the cell.
what happens to chromosomes, nuclear membrane and nuclei during telophase ii?
-chromosomes reach the poles
-nuclear membrane and nuclei reform.
_______ results in FOUR haploid cells.
cytokinesis
how many divisions that meiosis consists?
two
what does meiosis produce?
four unidentical haploid daughter cells
meiosis results in..
genetic variation
______ and _____ produce genetic variation among offspring.
meiosis and sexual reproduction
depending on how the chromosomes line up at the equator, how many gametes and different combinations of chromosomes can result?
four gametes and four different combinations
what is independent assortment?
random assortment of homologous chromosomes during meiosis i.
evolutionary adaptation depends on a population’s genetic variation as a result of…
sexual reproduction and mutations
what are the 4 characteristics of asexual reproduction?
-ONE individual
-ALL genes from ONE parent
-offspring IDENTICAL to parent
-results in a clone (NO variation)
what are the 4 characteristics of sexual reproduction?
-TWO individuals
-EACH parent contribute 1/2 of genes
-UNIQUE COMBINATION of 2 parents.
-genetic variation results
contrast asexual and sexual reproduction.
ASEXUAL REPRODUCTION:
-organism INHERITS ALL of its chromosomes from a single parent.
SEXUAL REPRODUCTION:
-beneficial genes multiply FASTER over time.
what is genetics?
scientific study of heredity
who is Gregor Mendel?
-Austrian monk and scientist.
-studies inheritance of traits in pea plants
-1860s
what is inheritance or heredity?
the passing of traits to the next generation.
what does Mendel performed in pea plants?
cross-pollination
what does self-fertilize or self-pollination mean?
pollen from stamens fertilize eggs (ova) in the pistil of the same flower.
define trait.
any characteristic that can be passed from parents to offspring.
define hybrid.
-organism that receives DIFFERENT genetic infromation for a trait from each parent.
-so called HETEROzygous.
define pure-bred.
-group of organisms that produce ONLY offspring with a given parental trait when allowed to self-fertilize.
-so called HOMOzygous.
parent generation is also known as the..
P generation.
the offspring of this P cross is called the..
first filial (F1) generation.
the offspring of this generation is from the F1 cross.
second filial geneartion (F2)
in this generation, the short trait HAD NOT disappeared but was suppressed by the tall trait.
F1.
what does Mendel proposed about traits?
traits are determined by factors and that an organism receives on factor from each parent.
define gene (factors)
unit of heredity information that controls the traits of a particular organism.
where is genes (factors) located?
chromosomes
what is alleles?
an alternative form of a single gene passed from generation to generation.
what is the difference between gene and allele.
gene determines a particular trait
allele determines the possible form of the gene
define dominant and recessive trait.
dominant trait is expressed preferentially in the phenotype of a hybrid.
recessive trait is not expressed in the phenotype of a hybrid.
an organism with two of the same alleles for a particular trait is…
homozygous
an organism with two different alleles for a particular trait is…
heterozygous
difference between genotype and phenotype.
genotype is the organism’s allele pairs
phenotype is the observable characteristic (appearance) or outward expression of an allele pair.
Mendel’s Law of Segregation
two alleles for a character are packaged into separate gametes.
each pair of alleles segregates, or separates, during..
meiosis
what happens to homologous chromosomes at anaphase I?
pull apart
In Mendel’s Law of Segregation, what happens during fertilization?
two alleles for that trait unite.
heterozygous organisms are called..
hybrids
Mendel’s Law of Dominance (define)
two alleles in a gene pair are different (heterozygous genotype), one allele can control the trait and the other can be hidden.
what allele always control a trait?
dominant
what allele is hidden when paired with another allele?
recessive
recessive allele is only expressed when…
there is no copy of the dominant allele for the gene.
define Mendel’s Law of Independent Assortment
random distribution of alleles occurs during gamate formation during metaphase I.
In Mendel’s Law of Independent Assortment, what ahppens during meiosis?
genes on separate chromosomes sort independently.
In Mendel’s Law of Independent Assortment, what happens to each paur of alleles (gene pairs)?
they segregates into gametes randomly and independently.
define monohybrid cross.
cross that involves hhybrids for a single trait.
define dihybrid cross.
simultaneous inheritance of two or more traits in the same plant
heterozygous for both traits.
what does punnett square predicts?
possible offsspring of a cross between two known genotypes.
what can be produced in the punnett square of dihybrid cross?
four types of alleles from the male gametes and four types of alleles from the female gametes.
what is the resulting phenotypic ratio for punnett square of dihybrid cross?
9:3:1:1
the new ccombination of genes are produced by?
crossing over and independent assortment
what is the exception in Mendel’s law of independent assortment?
gene linkage on a chromosome results
why gene linkage is an exception in Mendel’s law of independent assortment?
because gene linakge usually do not segregate independently.
what is polyploidy?
the occurence of one or more extra sets of all chromosomes in an organism.
