4th Form Definitions and Key Concepts Flashcards
diffusion
the net movement of substances from an area of high to low concentration, down a concentration gradient and can be across a partially permeable membrane
osmosis
the net movement of water from an area of high to low water potential, down a water potential gradient and can be across a partially permeable membrane
active transport
the movement of substances from an area of low to high concentration, against a concentration gradient, using the energy from ATP
phloem
a tissue in plants that is specialised to transport sugars and amino acids both up and down the plant from the leaves to respiring tissues. this is called translocation
translocation
the movement of sugars and amino acids through the phloem
transpiration
water loss via evaporation through the stomata in the leaves down a water potential gradient
transpiration stream
the upwards movement of water through the xylem from roots to leaves
xylem
a tissue that is specialised to transport water from the roots to the leaves. Is dead and hollow to allow the continuous column of water
antidiurectic hormone (ADH)
a hormone produced by the pituitary gland that increases the reabsorption of water in the collecting duct of the kidney
bladder
the organ that collects and holds urine before it is excreted
Bowman’s capsule
structure at the start of the nephron where the glomerular filtrate enters from the glomerulus and connects to the proximal convoluted tubule
collecting duct
final part of the nephron which connects to the ureter where water is reabsorbed, how much is determined by its permeability which is controlled by ADH
convoluted tubules
tubes in the nephron (PCT and DCT) where the filtrate flows through, substances (glucose, ions, amino acids) from the filtrate are reabsorbed by active transport into the blood from these tubes
excretion
the removal of metabolic waste from the body (co2 for example)
glomerulus
a bundle of capillaries where ultrafiltration occurs
loop of henle
part of the nephron after the PCT where water and salts are reabsorbed
nephron
functional unit of the kidney that contains the bowman’s capsule, PCT, Loop of Henle, DCT and collecting duct
organs of excretion
any organ that removes metabolic waste, the lungs removing carbon dioxide and water vapour produced from respiration, the kidneys removing water, urea and salts and the skin excreting water and salts
osmoregulation
regulation of the volume of water in body fluids by the use of the hormone ADH
selective reabsorption
the selective uptake of useful substances such as glucose, water and ions back into the blood from the nephron. selective reabsorption in the PCT involves the active transport of glucose out of the PCT back into the blood
stomata
small holes found in the lower epidermis that open and close thanks to the guard cells. control the loss of water by closing during the night but open during the day thanks to the guard cells to allow the diffusion of carbon dioxide and oxygen
ultrafiltration
the filtration of blood at the glomerulus under high pressure to form the glomerular filtrate. contains water, ions, glucose, urea and other molecules. does not contain proteins and blood cells as they are too large and cannot leave due to the basement membrane
ureter
tubes that carry urine from the kidneys to the bladder
urethra
tube that carries urine from the bladder out of the body
urine
waste product of the kidney that contains water, urea and ions
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
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
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
amniotic fluid
the fluid that surrounds and protects the embryo from bumps and sudden changes from the mother in the uterus
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
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)
embryo
an unborn organism in an early stage of development formed by mitosis
fertilisation
the fusion of the nucleus of a male and female gametes to form a diploid zygote
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
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.
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
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
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
monohybrid cross
a cross between two organisms that is used to investigate the inheritance of a single gene
oestogen
female reproductive hormone that causes the uterus lining to develop. It inhibits FSH. also responsible for the development of the secondary sexual characteristics
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
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
wind pollinating flowers
exposed stigma and stamen, dull/colourless flowers, no nectar, small and smooth pollen grains, feathery stigma
insect pollinating flowers
enclosed stigma and stamen, large, colourful petals with nectar present, stigma is sticky and large, sticky pollen grains