year 10 biology autumn term

how are lungs adapted for efficient exchange of gases?

Lungs are adapted for efficient gas exchange through:

• large surface area provided

• thin walls for rapid diffusion

• a rich blood supply that maintains a concentration gradient.

explain active transport

Active transport is the process by which cells:

• Move molecules against their concentration gradient

• This mechanism is essential for the uptake of nutrients into the cell

• requires energy

explain why a thin layer of epidermis is used and iodine solution is used

• A thin layer of epidermis allows for efficient diffusion of substances and minimises the distance for exchange

• iodine solution is used to indicate the presence of starch, highlighting areas of absorption.

explain why the cover slip is lowered onto the onion epidermis at an angle

Lowering the cover slip at an angle:

• prevents air bubbles from forming, ensuring a clear view of the specimen and allowing for better observation of the cells.

explain how the investigation could be modified to determine the concentration of the solution

By using:

• a series of solutions with varying concentrations

• measuring the rate of absorption or diffusion to compare the effects on the onion epidermis.

define diffusion

• molecules move from an area of higher concentration to an area of lower concentration

• resulting in even distribution.

osmosis

the movement of water molecules across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration,

• aiming to achieve equilibrium.

calculate magnification

magnification = size of image / actual size of object.

electron vs light microscope

• Electron microscopes use electrons for imaging and have higher resolution

• Light microscopes use visible light and are suitable for observing live specimens.

what is a gene

• a segment of DNA that contains the instructions for building proteins

• which determine an organism's traits and functions.

what are chromosomes

a coiled strand of DNA that contains many genes

how many chromosomes in 1 human body cell

46, 23 pairs

why do cells divide to make new cells

to grow or repair

name given to new cells produced during cell division

Daughter cells

mitosis

a type of cell division that results in two identical daughter cells.

describe the first stage of the cell cycle

• the dna is replicated and the nuclear membrane breaks down

• cells size increase

describe the second stage (mitosis) of the cell cycle

• chromosomes line up along the centre of the cell

• the chromatids (one of the two identical halves of a chromosome that has been replicated in preparation for cell division) separate from each other

describe the third stage of the cell cycle

• the chromatids move around the cell

• the cytoplasm/cell begins to divide

• this is called cytokinesis

how are living things orginised

atoms→molecules→cells→tissues→organ→organ system→organism

what is a organ system

a system made up of multiple organs that work together

what is digestion

• the breakdown of food from large, insoluble molecules into small soluble molecules

• which can be absorbed into the blood stream

• absorption happens in your small intestine

what are enzymes

• biological catalysts which speed up reactions in living things without being used up

what are the 3 stages of enzymes reacting

1. enzyme + substrate

2. enzyme substrate complex

3. enzyme + products

carbohydrase

• breaks down starch→glucose

• site of production and action in salivary glands, mouth and pancreas

protease

• breaks down meat, fish, cheese→amino acids

• site of production in the stomach, pancreas and small intestine

• site of action in stomach and small intestine

lipase

• breaks down fats + oils→fatty acids

• site of production in pancreas and small intestine

• site of action in small intestine

what is the role of bile

• emulsifying lipids, breaking them up into tiny droplets. Meaning they have a larger SA, lipase work better

• neutralises stomach acid

what is denaturisation

• an enzymes active site changes shape

• cannot create a enzyme substrate compound

what happens to enzymes when the temperature is too low/high

• low: less energy, not alot of kinetic energy/collisions

• high: change shape/denature

optimum temperature for enzymes in the human body

37*C

structure and function of red blood cell

• biconcave shape, haemoglobin to make red, no nucleus to carry more oxygen

• carries oxygen, distributes around your body to respire

structure and function of white blood cell

• contains nucleus, larger than red blood cell

• lymphocytes (produce antibodies) and phagocytes (engulf and digest invading microorganisms)

structure and function of platelets

• fragments of cells, no nucleus

• clots your blood to cause a scab to prevent microorganism entering your body and excessive blood loss

structure and function of plasma

• yellow colour, no red blood cells

• carries water, proteins, ions, nutrients and hormones

• maintains PH and temperature

artery

• to carry blood away from your heart to your body

• narrow

• thick walls, to stand pressure

• oxygenated blood

capillary

• to transport blood, nutrients and oxygen to cells in your organs & body

• capillaries to veins

• narrow

• one cell thick wall

• carries oxygenated & deoxygenated blood

vein

• to collect oxgyen-poor blood and return it to your heart

• wide

• thin walls

• carries deoxygenated blood