GCSE AQA Combined Science Biology Paper 1

Gene

a segment of DNA that determines characteristics of your body

How many chromosomes do humans have?

46 (23 pairs)

How many chromosomes do gametes (sex cells) have?

23

Mitosis

The process of cell division, resulting in two identical cells

The cell cycle

The cycle of your body's cells dividing in a series of stages

How long does the cell cycle take?

Anywhere from 24 hours to years (depending on the organisms stage of life)

Cell division in organisms

Pre-born baby- quick and constant
Child afterbirth- Fairly rapid
End of Puberty and Adulthood- slows drastically

Stage 1- Cell Cycle

-Longest stage
-Grows bigger
-Increased mass
-Duplicate their DNA
-Increase number of ribosomes, mitochondria, etc. for cell divide

Stage 2- Cell Cycle

-Mitosis occurs
-Organelles get pulled apart and nucleus splits

Stage 3- Cell Cycle

-Cytoplasm and Cell membrane split
-Two identical daughter cells

Cloning

Producing identical offspring

Zygote

A fused egg and sperm cell

embroyonic stem cells

Inner cells of the embryo

Embryo

One half of the zygote

adult stem cells

An undifferentiated cell of any organism that can rise to many more cells of the same type

Problems with embryonic stem cells

-Human rights debate
-Slow, expensive, unpredictable
-Possibly cause cancer
-Potentially infected with viruses

Therapeutic cloning

research using cells from an adult to produce a cloned embryo of themselves

Stem call research could possibly treat:

-Spinal cord injuries
-Diabetes
-Eyesight
-Heart damage
-Damaged bone and cartilage

Tissue

A group of similar cells that perform the same function.

Organs

Groups of tissues that work together to perform a specific function or related functions

Organ system

group of organs that work together to perform a specific function

Organ Systems in our body

Digestive system, respiratory system, and the circulatory system

Levels of organization (small to large)

cell, tissue, organ, organ system, organism

Digestive system

body system the breaks down food and absorbs nutrients (digestion occurs)

Enzymes

break down large molecules for digestion to occur

Small intestine

absorption of molecules into your blood

Function of muscular walls of the small intestine

Squeeze undigested food into your large intestine

Liver

produces bile

Stomach

breaks down and digests food into order to extract nutrients

Large intestine

absorbs water and leaves waste to be stored and passed out as faeces

Main compounds of a cell

Carbohydrates, lipids and proteins

Carbohydrates Function

main source of energy

Simple carbhydrates

composed of only one or two units of sugars e.g Sucrose

Complex carbohydrates

composed of long chains of simple sugar units bonded

Lipids

-fats and oils
-insoluble in water
-made of carbon, hydrogen, oxygen
-Made up of three fatty acids joined to glycerol

Proteins function

build, maintain and repair tissue and cells in body

How much of your body mass is protein?

15-16%

What are proteins made of?

carbon, oxygen, nitrogen, hydrogen

What composes a protein molecule?

long chains of amino acids (amino acids are the building blocks of protein)

Denatured

loss of an enzyme's normal shape so that it no longer functions

What causes something to become denatured?

a less than optimal pH and temperature

jobs of proteins

structural components of tissues e.g muscles
hormones e.g insulin
antibodies
enzymes

catalyst

substance that speeds up the rate of a chemical reaction

Enzyme

protein that acts as a biological catalyst

lock and key model

The model of the enzyme that shows the substrate fitting perfectly into the active site

Metabolism

All of the chemical reactions that occur within an organism

Enzyme activity is affected by

temperature and pH

temperatures affects on enzyme activity

Higher temperatures denature the enzyme and change the shape of the active site

Ph affects on enzyme activity

interferes with the forces between proteins (where the enzyme comes from), therefore the shape changes, and can no longer act on that site

digestive enzymes

work outside your cells, unlike regular enzymes, found in the lining of the digestive system

Carbohydrases

enzymes that speed up the breakdown of carbohydrates into simple sugars

Amalyse

breaks down carbs

Protease

enzyme that breaks down proteins

Where is amylase produced?

mouth and small intestine

Where is protease produced?

Stomach, pancreas, small intestine

Lipase

enzyme that breaks down fat

Where is lipase produced?

Pancreas and small intestine

What is pepsin?

protein digesting enzyme

Stomach mucus layer

protects the stomach wall and protects it from being digested by acid and emzymes

What is Bile

q greenish alkaline fluid that aids digestion and is

Where is bile produced?

liver

Where is bile stored?

gallbladder

function of bile

break down fats

The speed lipase breaks down fats and converts them is increased with

surface area

Components of blood

plasma, red blood cells, white blood cells, platelets

Plasma

Liquid part of blood that transports all blood cells and other substances around the body

red blood cells

Blood cells that carry oxygen from the lungs to the body cells.
- no nucleus
-packed with haemoglobin
-biconcave discs (increased surface area from being pushed in)

Haemoglobin

the red pigment that carries oxygen around the body in the red blood cells

white blood cells

Blood cells that perform the function of destroying disease-causing microorganisms

platelet

cell fragment released by bone marrow that helps in blood clotting

Arteries

Blood vessels that carry blood away from the heart

Veins

Blood vessels that carry blood back to the heart

Capillaries

any of the fine branching blood vessels that form a network between the arterioles and venules.

Double circulatory system

the circulation of blood from the heart to the lungs is separate from the circulation of blood from the heart to the rest of the body

coronary arteries

blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle

Atria

the two upper chambers of the heart

vena cava

a large vein carrying deoxygenated blood into the heart

pulmonary veins

Deliver oxygen rich blood from the lungs to the left atrium

Ventricles

the two lower chambers of the heart

pulmonary artery

artery carrying oxygen-poor blood from the heart to the lungs

Aorta

The large arterial trunk that carries blood from the heart to be distributed by branch arteries through the body.

coronary heart disease

the clogging of the vessels that nourish the heart muscle, treated with stent or bypass and often prescribed statins

stent

wire-mesh tube used to keep arteries open

Statins

drugs used to lower cholesterol in the bloodstream

bypass

a medical operation on the heart in which blood is directed along a different route so that it does not flow through a part that is damaged or blocked

leaky valves

When valves in the heart become stiff and do not open fully

Mechanical valves

mad made valve but must be on medication for life, e.g made from titanium

Biological Valve

last 12-15 years, no medication, e.g made using pig valves

resting heart rate

70-80 bpm

pacemaker

A device that delivers electrical impulses to the heart to regulate the heartbeat when your natural pacemaker fails

artificial heart

a pump designed to fit into the human chest cavity and perform the heart's function of pumping blood around the body

Lungs

Main organs of the respiratory system

lungs location

Either side of the heart in the chest cavity; protected by the rib cage; base rests on the diaphragm

Diaphragm

Large, flat muscle at the bottom of the chest cavity that helps with breathing

breath in

oxygen rich air moves into lungs
-oxygen constantly diffuses into the bloodstream

breath out

removes carbon dioxide rich air out of the lungs
-carbon dioxide constantly diffuses into the air

Alveoli

air sacs in the lungs

Alveoli adaptations

- thin walls make diffusion easy as there is a short diffusion distance
- spherical shape of the alveoli gives large surface area for diffusion

Epidermal tissue

forms the outer protective covering of a plant

palisade mesophyll

photosynthetic tissue