Must Know Biology Facts

Blood in the heart

Body Tissues → Vena Cava → Right Atrium → Right Ventricle → Pulmonary Artery → Lungs → Pulmonary Vein → Left Atrium → Left Ventricle → Aorta → Body Tissues

Starch Test (Photosynthesis Test)

Boil leaf in water (kills it, stopping chemical reactions) → Boil leaf in ethanol to remove chlorophyll → Soak in warm water (rehydrate it) → Add iodine solution

Blue-black means starch is present.
Yellow-brown means no starch.

Protein Test

Biuret indicator goes purple in protein, light blue if no protein.

Reflex Arc

• Receptor detects a stimulus (e.g., touching something hot).

• Sensory neuron carries the impulse to the spinal cord.

• Relay neuron in the spinal cord passes the impulse to a motor neuron.

• Motor neuron carries the impulse to an effector (e.g., a muscle).

• Effector (muscle or gland) responds (e.g., pulling hand away).

Glucose test

Heat with benedict’s solution, brick red positive result, if slightly positive just orange/yellow, remains blue if negative.

Lipids

Emulsion test, mix with ethanol and then add water, milky-white emulsion if positive, clear if not.

Xylem

transports water and minerals upwards, made of dead cells.

Phloem

transports sugar (glucose), either direction, made of living cells

Arteries

Carry blood away from heart, thick walls, high pressure.

Veins

Carry blood towards heart, thin walls, walves prevent blackflow.

Hormones VS Nerves

Nervous Speed = Fast (Slow in hormones)
Nervous Duration = Short-lived (long in hormones)
Transmission = Electrical (Chemical in hormes)

Eyes

Bright light; pupil constricts.

Dim light; pupil dilates

Distant object; lens flattens.

Near light; lens thickens

ADH Hormone

Controls water balance by making sure kidney reabsorbs more/less water.

Mitosis

Produces identical body cells

Meiosis

Produces gametes with half the chromosomes

Natural selection

Variation exists, mutation causes something, humans with that trait can live and reproduce better (explain why specific feature does that), passing on their genes/allele to next generation.

Eutrophication

excess nutrients lead to algal bloom, killing fish.

Menstrual cycle

Days 1-5
FSH stimulates egg to mature in ovary, stimulates ovary to produce oestrogen

Days 5-14

Oestrogen thickens uterus lining and reduces FSH stopping multiple eggs from maturing, stimulates release of LH

Day 14

Ovulation (release of egg from ovary) due to LH (from pituitary gland). Stops LH and FSH

Day 14-28
Progesterone from ovary maintains uterus lining to support egg, inhibits LH and FSH from making another egg.

If no pregnancy, progesterone drops and uterus lining sheds if does occur then progesterone stays high to keep uterus lining lit.

Antibodies/Vaccination

Body is inoculated against the baddies, so antigens remain, so secondary immune response is more effective as memory cells remember what antibodies to make and are able to make them in large quanitites and quicker.