Key Definitions - Reproduction and Inheritance Flashcards
define follicle stimulating hormone (FSH).
a hormone produced by the pituitary gland that stimulates the growth of follicles in the ovary and stimulates the release of oestrogen
define luteinising hormone (LH).
a hormone secreted by the pituitary gland that stimulates ovulation (the release of an egg from the ovary) and the release of progesterone.
define progesterone.
a hormone produced in the ovaries, specifically by the corpus luteum and the placenta that maintains the uterus lining and inhibits the release of FSH and LH.
define amniotic fluid.
the fluid that surrounds and protects the embryo from bumps and sudden changes from the mother in the uterus
define asexual reproduction.
a form of reproduction involving a single parent CELL. It created genetically identical offspring which have survival value in a stable environment. Usually producing large numbers of offspring and quickly
define cuttings.
method of cloning plants. A section of the stem is cut, with at least one leaf, from a parent plant that you want to clone and is replanted in damp compost with hormones that stimulate root growth (auxins)
define embryo.
an unborn organism in an early stage of development formed by mitosis
define fertilisation.
the fusion of the nucleus of a male and female gametes to form a diploid zygote
define gametes.
sex cells, sperm in males and egg cells in females, each being haploid (half the number of chromosomes). Pollen is the male gamete of a plant
define germination.
seeds need oxygen (for respiration), warmth (for enzymes), water (activate enzymes) to germinate. This occurs until photosynthesis can take place in the leaves, then germination has finished.
define menstrual cycle.
a monthly cycle in women that involves the growth of the uterus lining, release of an egg, maintenance of the uterus lining and then its shedding
define meiosis.
a form of cellular division that produces gametes, genetically different, haploid cells. 4 daughter cells produced over two divisions involving two parent CELLS only occurs in the reproductive organs and used to produced gametes
define mitosis.
a form of cellular division that produces two genetically identical, diploid cells from a single parent CELL. 2 daughter cells produced over one division, occurs everywhere in the body and used for the growth and repair of cells/tissues
define monohybrid cross.
a cross between two organisms that is used to investigate the inheritance of a single gene
define oestrogen.
female reproductive hormone that causes the uterus lining to develop. It inhibits FSH. Also responsible for the development of the secondary sexual characteristics
define placenta.
attached to the uterus lining during pregnancy. Acts as an exchange surface between the mother and foetal blood where glucose (for respiration), amino acids (for protein synthesis) and oxygen (for respiration) diffuse into the foetal blood and waste products like carbon dioxide and urea diffuse into the mother’s blood. Also produces progesterone
define pollination.
transfer of pollen grains (either by wind or insects) from the anther to the stigma, where fertilisation occurs. Can be self-pollination (same flower) or cross pollination (flowers on different plants). Also wind or insect pollination
define wind pollinating flowers.
exposed stigma and stamen, dull/colourless flowers, no nectar, small and smooth pollen grains, feathery stigma
define insect pollinating flowers.
enclosed stigma and stamen, large, colourful petals with nectar present, stigma is sticky and large, sticky pollen grains
define secondary sexual characteristics.
features that appear during puberty and differ between genders. Examples; voice changing, growth of hair, development of breasts, hips widening, growth of male reproductive organs, start of menstrual cycle
define sexual reproduction.
a form of reproduction that involves the fusion of male and female gametes, creating genetic variation in the offspring and has survival value in a changing environment. Involves two parent CELLS
define testosterone.
the main male reproductive hormone, produced by the testes, stimulates sperm production (along with FSH) and responsible for the development of male secondary sexual characteristics
define zygote.
a fertilised egg cell (diploid)
define allele.
an alternative version of a gene that cause difference in inherited characteristics such as hair colour
define chromosome.
a long, coiled molecule of DNA that carries genetic information in the form of genes
define codominance.
two different alleles both being expressed in the phenotype
define deoxyribonucleic acid (DNA)
double stranded polymer arranged in a double helix, made up of DNA nucleotides that carry the genetic code. There are 4 DNA nucleotides, each made up of a phosphate molecule and a deoxyribose sugar but differ due to their nitrogenous base, adenine, thymine, cytosine and guanine
define dominant.
the allele that is always expressed in the phenotype when in the genotype, denoted by a capital letter
define evolution.
the change in inherited traits within a population over time. Modelled by natural selection
define gene.
a section of DNA that codes for a specific sequence of amino acids that forms a protein and is responsible for a particular trait (phenotype)
define genome.
the complete genetic material of an organism
define genotype.
all of the alleles present in an organism
define haploid.
a cell that contains half the amount of genetic information. Human gametes have 23 chromosomes (it only contains 1 chromosome of each homologous pair)
define heterozygous.
when an organism has two different alleles of a gene, e.g. Gg
define homozygous.
when an organism has two of the same alleles, e.g. GG/g
define mutagens.
chemicals that increase the frequency of mutations in DNA
define mutation.
a random change in DNA which may result in genetic variations that can produce a slightly different protein and therefore a different phenotype if the mutation occurs in a gene. Examples being addition, substitution and deletion
define natural selection.
a change in the environment (selection pressure) causes an organism with a mutated allele to be at an advantage, they are more likely to survive, reproduce and pass on their advantageous, mutated allele to their offspring. This happens over many generations and results in the mutated allele becoming more frequent in the population at the expense of the previously dominant allele
define nucleus.
an organelle found in most eukaryotic cells that contain the genetic material of the cell and controls the activities of the cell
define phenotype.
an organisms visual characteristics due to the organism’s genotype and interactions with the environment. E.g. hair colour
define recessive.
an allele that is only expressed in the phenotype when present with another recessive allele in the genotype (homozygous). Denoted by a lower case letter, e.g. q
define sex chromosomes.
a pair of chromosomes that determine the sex of an individual. In humans this is the 23rd pair and is XX in females and XY in males
define variation.
the differences between individuals due to genes, the environment or a combination of both
