science revision

Question 1

Genetics

Answer 1

the study of genes, heredity, and genetic variation in living organisms.

Question 2

DNA

Answer 2

a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all living things.

Question 3

Chromosome

Answer 3

a long, thread-like structure composed of DNA and protein found in the nucleus of most living cells.

Question 4

Gene

Answer 4

a sequence of DNA or RNA that encodes the synthesis of a functional molecule such as a protein or RNA molecule.

Question 5

Haploid

Answer 5

a cell or organism containing a single set of chromosomes.

Question 6

Diploid

Answer 6

a cell or organism containing two sets of chromosomes.

Question 7

Gamete

Answer 7

a specialized cell that combines with another to form a zygote, which develops into a new individual.

Question 8

Somatic

Answer 8

relating to the body, especially as distinct from the mind.

Question 9

Helix

Answer 9

a three-dimensional shape like that of a wire spiral or a DNA molecule.

Question 10

Complementary base pairs

Answer 10

specific pairs of nucleotides that form the rungs of the DNA ladder: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).

Question 11

Heredity

Answer 11

the passing of traits from parents to offspring.

Question 12

Karyotype

Answer 12

the number and appearance of chromosomes in the nucleus of a eukaryotic cell.

Question 13

Autosomes

Answer 13

any chromosome that is not a sex chromosome.

Question 14

Genome

Answer 14

all of an organism’s genetic material, including chromosomes and cytoplasmic DNA.

Question 15

Nucleotide

Answer 15

the basic building blocks of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Question 16

Interphase

Answer 16

the period of the cell cycle between mitotic divisions when the cell grows, copies its DNA, and prepares for cell division.

Question 17

Replication -

Answer 17

the process of copying DNA to form new DNA molecules.

Question 18

Meiosis

Answer 18

a type of cell division that results in four daughter cells each with half the number of chromosomes as the parent cell.

Question 19

Mitosis

Answer 19

a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus.

Question 20

Chromatids

Answer 20

one of the two identical halves of a replicated chromosome.

Question 21

Allele

Answer 21

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Question 22

Homozygous

Answer 22

having two identical alleles for a particular gene.

Question 23

Heterozygous

Answer 23

having two different alleles for a particular gene.

Question 24

Phenotype

Answer 24

the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.

Question 25

Genotype

Answer 25

the genetic makeup of an organism, as determined by the combination of alleles inherited from its parents.

Question 26

Purebred

Answer 26

an organism that is homozygous for all genes studied.

Question 27

Hybrid

Answer 27

an organism that is heterozygous for one or more genes.

Question 28

Dominant trait -

Answer 28

a genetic trait that results from a dominant allele and is expressed in the phenotype even when the heterozygous state exists.

Question 29

Recessive trait -

Answer 29

a genetic trait that results from a recessive allele and is expressed in the phenotype only when the homozygous state exists.

Question 30

Locus -

Answer 30

the specific location of a gene on a chromosome.

Question 31

Evolution -

Answer 31

the process of gradual change in the genetic makeup of a population of organisms over time.

Question 32

Generation

Answer 32

a group of organisms that are contemporaries and are descended from a common ancestor.

Question 33

Ancestor

Answer 33

a person, animal, or plant from which one is descended.

Question 34

Homologous

Answer 34

structures or genes that are similar in structure or sequence because they have a common ancestor.

Question 35

Analogous

Answer 35

structures or genes that perform similar functions but have different evolutionary origins.

Question 36

Distribution -

Answer 36

the geographic range of a particular species or group of organisms.

Question 37

Variation

Answer 37

a difference in a physical or genetic trait among individuals in a population.

Question 38

Inheritance -

Answer 38

the transmission of genetic information from one generation to the next.

Question 39

Offspring

Answer 39

the biological progeny of an organism

Question 40

Population -

Answer 40

a group of individuals of the same species living in the same geographic area.

Question 41

Fossil -

Answer 41

the preserved remains or traces of an organism that lived in the past.

Question 42

Comparative anatomy -

Answer 42

the study of similarities and differences in the anatomy of different species.

Question 43

Embryology

Answer 43

the study of the development of embryos and fetuses.

Question 44

Pentadactyl -

Answer 44

having five digits on hands and feet.

Question 45

Speciation -

Answer 45

the formation of new and distinct species in the course of evolution.

Question 46

Biodiversity -

Answer 46

the variety and variability of life on Earth, including the number of species and their genetic diversity.

Question 47

Isolation -

Answer 47

a barrier that prevents or restricts the exchange of genes between populations of a species.

Question 48

Selection -

Answer 48

the process by which certain traits become more or less common in a population over time.

Question 49

Interbreeding -

Answer 49

the breeding of individuals from different populations or species.