Biology Paper 2 - Ultimate Wordlist

Producer

the first organism in a food chain which produces its own food

Photosynthesis

the process in which green plants use sunlight to convert CO2 and water to glucose and oxygen

Chloroplast

green disc containing chlorophyll, makes glucose through photosynthesis

Endothermic

a reaction where the products contain more energy than the reactants, e.g. Photosynthesis because it absorbs light energy

Starch

carbohydrate made by the joining of glucose molecules

Limiting factor

a single factor that when in short supply can limit the rate of photosynthesis

Directly proportional

when the percentage change of a variable occurs with an equal percentage change of another variable, makes a straight line graph

Inversely proportional

where one variable increases at the same rate as another decreases

Inverse square law

where a quantity varies in inverse proportion of the square of the distance from the source of the quantity

Root hair cell

cells in the roots with a large surface area and thin cell walls to increase the rate of osmosis and active transport.

Xylem

transports water and mineral ions up from the roots to the leaves; provide support for the plant via lignin fibres. For transpiration

Lignin

thicken the outer cell walls of the xylem vessels. Is rigid and waterproof to keep the water in the xylem

Xylem vessel

made of dead xylem cells with no top or bottom cell walls to become a long tube for transpiration

Phloem

carry sugars and amino acids made in the leaves to other parts of the plant for use or storage. Materials are dissolved in water. Translocation

Sieve tubes

cells in the phloem arranged in long columns. They have cell walls, a thin layer of cytoplasm but no nucleus. They have sieve plates for liquids and dissolved nutrients to pass through

Companion cells

support the sieve tubes; have dense cytoplasm

Sucrose

the type of sugar found in the phloem of plants

Transpiration

The loss of water vapour from plant leaves due to the movement of water upwards through the plant xylem.

Translocation

occurs in either direction, is the transportation of sugars and amino acids in solution

Diffusion

movement of particles from a high concentration to a lower concentration

Osmosis

the net movement of water across a partially permeable membrane from a dilute to a concentrated solution OR high water pot. to a low water pot.

Active transport

the movement of particles against a concentration gradient, requires energy, uses protein pumps. e.g. uptake of mineral ions

Stomata

small openings on the surface of leaves that allow for gas exchange

Guard cells

can open and close the stomata

Palisade mesophyll

tall, column-shaped cells near the upper surface of a leaf, containing many chloroplasts

Spongy mesophyll

plant tissue in a leaf with loosely packed cells with air pockets for gas exchange

Epidermis

the transparent, outermost layer of the leaf

Waxy cuticle

the waxy layer on the top of the leaf to protect it and stop water evaporating from the top layer

Potometer

a device which measures the rate of water uptake (transpiration)

Xerophyte

a plant adapted to reduce water loss to enable it to survive in dry conditions

Deciduous

a plant that loses its leaves in the winter to conserve energy

Tropism

plant hormone causing growth or turning towards a stimulus

Phototropism

plant hormone responding to light

Geo/gravitropism

plant hormone responding to gravity

Auxin

chemical substance produced at the tip of the stem which stimulates cell elongation

Gibberellin

plant hormone that stimulates seed germination and flower and fruit growth

Ethene

plant hormone that stimulates fruit ripening

Weedkiller

a substance that kills weeds

Germination

the process in which a plant grows form a seed

Parthenocarpy

development of fruit without fertilisation

Rooting powder

contains plant hormones, to speed up the growth of roots

Photoperiodism

the response of an organism to the number of daylight hours in a day

Hormone

Cell signalling molecule produced by endocrine glands and released into the blood. It travels to a target organ and binds to receptors on effectors, initiating a response.

Endocrine glands

Glands that secrete hormones directly into the bloodstream.

Pituitary gland

An endocrine gland that produces hormones which control other glands. Often described as the 'master gland'.

Thyroid gland

An endocrine gland located in the neck that produces thyroxine.

Adrenal glands

Endocrine glands located above the kidneys that produce adrenaline.

Target organ

The organ at which a hormone is targeted.

Metabolic rate

Rate at which biochemical reactions occur in cells.

Thyroxine

A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature.

TRH (Thyrotropin-releasing hormone)

A hormone secreted by the hypothalamus when blood thyroxine levels are lower than normal. It stimulates the pituitary gland to release TSH.

TSH (Thyroid-stimulating hormone

Hormone secreted by pituitary gland that stimulates the thyroid gland to release thyroxine.

Negative feedback

A corrective mechanism that allows only small shifts from a set point, reversing a change in conditions.

Adrenaline

Hormone produced by adrenal glands which is involved in the fight or flight response. It increases heart rate, blood pressure, blood floe to muscles and blood glucose levels.

Testes

Pair of endocrine glands in males which secrete testosterone into the bloodstream.

Menstrual cycle

Monthly cycle in women that involves the development of the uterus lining, ovulation, maintenance of the uterus lining and its shedding.

Puberty

Period in which adolescents reach sexual maturity and become capable of reproduction.

Menopause

Natural biological process that marks the end of a woman's reproductive years.

Fertilisation

Process by which male and female gametes are fused together, initiating the development of a new organism.

Ovulation

The release of an egg from one of the ovaries. The egg travels down the fallopian tube, where fertilisation by a sperm may occur.

Menstruation/Period

Shedding of the uterus lining on day one of menstrual cycle.

Oestrogen

Female sex hormone released by the ovaries that causes the growth and repair of the uterus lining. High levels of oestrogen stimulate a surge in LH production.

Progesterone

A female sex hormone secreted by the corpus luteum that maintains the uterus lining. It also inhibits FSH and LH release.

Contraception

Method used to prevent pregnancy.

Barrier method

Type of contraception that prevents sperm and egg meeting e.g. condoms, diaphragms.

Combined pill

Contraceptive pill containing both progesterone and oestrogen.

FSH (follicle-stimulating hormone)

A hormone secreted by the pituitary gland that stimulates follicle cells to mature and secrete oestrogen.

LH (Luteinising hormone)

A hormone secreted by the pituitary gland that initiates ovulation and stimulates the development of the remains of the follicle into a corpus luteum.

Follicle

A fluid filled sac in the ovaries that contains an immature egg.

Corpus luteum

Temporary endocrine structure, formed from the remains of the follicle, that secretes progesterone.

ART (Assisted Reproductive Technology)

Fertility treatment in which a woman's eggs are handled outside the body.

Clomifene therapy

Where a drug is prescribed to women who do not ovulate regularly, which stimulates the secretion of more FSH and LH, triggering egg production and ovulation.

IVF (in vitro fertilisation)

Fertilisation of a sperm and an egg outside the body. Zygote is allowed to grow and the embryo is transferred into the uterus.

Insulin

A hormone secreted by the pancreas when blood glucose levels are too high. I causes liver and muscle cells to increase their uptake of glucose and the conversion of glucose to glycogen in the liver.

Glucagon

A hormone secreted by the pancreas when blood glucose concentration is too low. It causes the breakdown of glycogen to glucose in the liver.

Glycogen

Store of glucose in the liver and muscle tissues.

pancreas

Type 1 Diabetes

Where the pancreas fails to produce enough insulin. It is controlled by daily insulin injections, limiting refined sugar intake and getting regular exercise.

Type 2 Diabetes

When a person develops insulin resistance or doesn't produce enough insulin. It is often due to obesity and is controlled by eating a balanced diet and getting regular exercise.

Benedict's test

Test for reducing sugars. Heat the solution with Benedict's reagent and the mixture will turn from blue to brick-red precipitate in the presence of a reducing sugar.

Correlation

A mutual relationship between two or more things.

Risk factor

A factor which increases your chance of developing a disease.

BMI (Body mass index)

□(64&(mass (kg))/(h?igh? (m))2)

Waist : hip ratio

□(64&(waist circumference (cm))/(h?p circumference (cm))) Used to indicate abdominal obesity.

Vasoconstriction

Constriction of blood vessels near the surface of the skin. Less blood flows close to the skin surface, decreasing heat loss to the surroundings.

Vasodilation

Dilation of blood vessels near to the surface of the skin. More blood can flow closer to the skin surface, increasing heat loss to the surroundings.

Sweating

Release of liquid from body's sweat glands to cool the body down.

Shivering

Involuntary contraction of muscles which generates heat from respiration.

Thermoregulation

The maintenance of core body temperature.

Hypothalamus

Structure in the brain that contains the thermoregulatory centre. Coordinates information from receptors and sends instructions to the effectors.

Osmoregulation

Maintenance of constant water levels in the body fluids of an organism.

Osmosis

Net movement of water from an area of high water potential to low water potential across a partially permeable membrane.

Urethra

Tube that releases urine from the bladder, out of the body.

Ureter

Tube that takes urine from the kidneys to the bladder.

Bladder

Organ which stores urine.

Renal artery

Blood vessel that carries oxygenated blood to the kidneys.

Renal vein

Blood vessel that drains the kidneys.

Nephron

A functional unit of the kidney, which filters out small molecules from the blood.

Ultrafiltration

Removal of small molecules, water and ions, from the blood in the glomerulus at high pressure.

Glomerulus

Bundle of capillaries located in the capsule of a nephron, adapted for the filtration of blood.