u7 bio gcse double sci...

asexual reproduction

only one parent/cell involved, produces genetically identical offspring

sexual reproduction

two parents/parent cells involved, produces genetically unique offspring

puberty

period which during adolescents develop secondary sexual characteristics (phy changes in the body, growth spurts, body hair)

oestrogen

produced in ovaries, rebuilds uterus lining in preparation for pregnancy

progesterone

produced in ovaries, maintains uterus lining

zygote

fertilised egg

blastocyst

16 genetically identical cells

placenta

organ that serves as a site of exchange to allow exchange of nutrients, waste, oxygen btwn mother & child. is an endocrine gland that secretes oestrogen & progesterone for the uterus to remain intact

chromosome

large structure of condensed dna

diploid

a cell with pairs of chromosomes

dna

long molecule with genetic code

haploid

a cell with a single set of chromosomes

meiosis

nuclear cell division that makes genetically different gametes

mitosis

cell division that makes identical cells

gene

a section of a chromosome that codes for a protein

somatic cell

normal body cell

interphase (stage 1 of mitosis)

cell is preparing to divide, nucleus visible

prophase (stage 2 of mitosis)

chromosomes are easily seen & scattered throughout cytoplasm

metaphase (stage 3 of mitosis)

chromosomes line up along equator of cell

anaphase (stage 4 of mitosis)

chromatids separate and move apart

telophase (stage 5 of mitosis)

chromosomes collect at 2 poles of cell

chromatids

separate arms of replicated chromosome

cytokinesis

cell membrane & cyptoplasm split to form two cells

genome

entire genetic makeup of organism

allele

different version of a gene

dominant allele

allele which is always expressed even if there’s only one copy

recessive allele

allele which is only expressed if both copies are recessive

genotype

genetic makeup of an organism (the combination of alleles you have)

phenotype

physical characteristics of an organism

polygenic

when many genes interact to control one characteristic

autosome

non sex/body cell chromosome

sex chromosome

chromosome that determines biological sex

mutation

change in dna sequence of an organism

species

group of organisms that can interbreed & produce fertile offspring

evolution

a gradual change in the frequency of a phenotype in a population over many generations

selective breeding

process where humans choose which plants/animals will reproduce to inherit desired traits, leading to development of specific characteristics over time

bacteriocidal

kills bacteria

bacteriostatic

prevents bacteria from growing & reproducing

genetic engineering

modifying genome of organism by introducing gene from another organism to give a desired characteristic

prostate gland

produces semen which provides sperm cells with nutrients

sperm duct

sperm passes through to be mixed with semen before passing through urethra during ejaculation

urethra

tube running down centre of penis that can carry out urine & semen

testis

contained in scrotum, produces sperm & testosterone

penis

passes urine out of body from bladder & allows semen to pass into vagina during sexual intercourse

oviduct/fallopian tubes

connects ovary to uterus & is lined with ciliated cells to push ovum down to it. fertilisation occurs here

ovary

contains ova (fem gametes) which will mature and develop when hormones are released

uterus

muscular bag with soft lining where zygote will be implanted to develop into fetus

cervix

ring of muscle at lower end of uterus to keep the developing fetus in place during pregnancy

vagina

muscular tube that leads to inside of a woman’s body. where the male penis will enter during sexual intercourse

umbilical cord

joins embryo’s blood supply to placenta for exchange of nutrients & removal of waste products

variation

difference between individuals of same species

continuous variation

many small differences for a particular characteristic between individuals (such as height, weight, finger length)

discontinuous variation

many distinct differences for a particular characteristic between individuals (such as blood type & sex)

antibiotics

chemical substances made by certain bacteria/fungi that affect the working of bacteria by disrupting structure/function or by preventing them from reproducing

transgenic

transfer of genetic material from one species to a different species