year 8 - biology t3

define diffusion

movement of gas or liquid from an area of higher concentration to an area of lower concentration.

define breathing

breathing is a process that involves inhalation and exhalation. it is an involuntary action and does not require conscious thought.

define respiration

(cellular) respiration is the process that releases energy from energy-rich foods.

define excretion

process of removing waste products made by the body's cells from the body.

recall the major structural levels of organisation and describe how they group to work together

1. atoms - smallest units of elements (e.g. carbon, oxygen)

2. molecules - groups of atoms joined together (e.g. water)

3. cells - made up of molecules, basic units of life

4. tissues - groups of similar cells working together

5. organs - groups of different tissues working together for a specific function

6. organ systems - groups of organs working together to perform a major body function

7. organism - all the organ systems working together to make the whole living person

atoms → molecules → cells → tissues → organs → organ systems → organism

recall the word equation for cellular respiration

glucose + oxygen → carbon dioxide + water + energy

recall and identify the major structures of the respiratory system

(pharynx, larynx, trachea, bronchi, bronchioles, alveoli)

pharynx - passageway for air and food

larynx - air passageway, produces voice, prevents food and drink from entering lower respiratory system

trachea - connects larynx with bronchi leading to each lung, conducts air to and from bronchi

bronchi - two branches of trachea that conduct air from trachea to each lung

bronchioles - narrow passageways to conduct air from bronchi to alveoli

alveoli - microscopic chambers → sites of gas exchange

explain gas exchange and the major properties of alveoli that enhance the rate of diffusion

gas exchange is the movement of oxygen and carbon dioxide between the alveoli in the lungs and the blood:

• oxygen moves from air in the alveoli → blood stream because there is a higher concentration of oxygen in the alveoli

• carbon dioxide moves from blood → alveoli because there is a higher concentration of carbon dioxide in the blood

• movement occurs by diffusion, movement of particles from an area of high concentration to low concentration

alveoli are suited for gas exchange because they have:

1. thin walls which allows for easy diffusion

2. large blood supply

3. moist - makes it easier for gases to diffuse

4. large number of alveoli = increased surface area

explain breathing (inhalation and exhalation) and how changes in the diaphragm and the intercostal muscles affect chest volume, air pressure and air movement during this process.

breathing involves inhalation and exhalation. the diaphragm and intercostal muscles change the volume of the chest, which changes air pressure and causes air to move.

during inhalation, the diaphragm pulls down (contracts) and the intercostal muscles contract, moving the ribs up and out. as a result, the chest volume increases, and since the air pressure in the lungs decreases, air rushes into the lungs.

during exhalation, the diaphragm relaxes (pulls up) and the intercostal muscles relax, allowing ribs to move down and in and become smaller. as a result, the chest volume decreases, and since the air pressure in the lungs increases, air rushes out of the lungs.

recall the major components of blood (red blood cells, white blood cells, platelets and plasma) and describe their functions

red blood cells - carries oxygen from the lungs to body cells using haemoglobin, also carrying some carbon dioxide back to the lungs

white blood cells - helps protect body from disease. there are two main types of white blood cells - phagocytes and lymphocytes.

platelets - helps the blood clot when a blood vessel is damaged

plasma - liquid part of blood. there are many things dissolved and suspended in the liquid, and it transports these substances (e.g. amino acids, glucose, fatty acids, glycerol) to where they are required by the body.

recall the structure and describe the function of arteries, capillaries, and veins

there are three major types of blood vessels: arteries, capillaries, and veins.

arteries - thick, elastic muscular wall - helps deal with high pressure of blood from the heart, no valves - heart pump has enough force to stop back flow. carries blood away from the heart, and the blood is usually under high pressure caused by the heart

capillaries - one cell thick, which increases diffusion rate (speed), therefore makes gas exchange more efficient (faster), no valves, high in number → increases surface area (more sites for gas exchange). small vessels branches through tissues and organs, connects arteries to veins and allows oxygen, nutrients, carbon dioxide, and wastes to move between the blood and body cells

veins - thin walls with a large lumen (diameter), has valves to stop backflow. carries blood towards the heart, blood pressure is low

recall and identify the structures (chambers and valves) of the heart and major blood vessels leading into the heart

the heart has four chambers and four main valves. the chambers work together to pump blood around the body, while the valves prevent blood from flowing backwards.

• right atrium - receives deoxygenated blood from the body

• right ventricle - pumps deoxygenated blood from the lungs

• left atrium - receives oxygenated blood from the lungs

• left ventricle - pumps oxygenated blood to the rest of the body. it has the thickest muscular wall because it pumps blood at high pressure

four valves:

• tricuspid valve – between the right atrium and right ventricle.

• pulmonary valve – between the right ventricle and pulmonary artery.four chambers:

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• bicuspid valve – between the left atrium and left ventricle.

• aortic valve – between the left ventricle and aorta.

major blood vessels:

• superior vena cava - brings deoxgynated blood from the upper body to the right atrium

• inferior vena cava - brings deoxygenated blood from the lower body to the right atrium

• pulmonary veins - brings oxygenated blood from the lungs to the left atrium

• pulmonary artery - carries deoxygenated blood from the right ventricle to the lungs

• aorta - carries oxygenated blood from the left ventricle to the body

recall and identify the vessels of the pulmonary and systemic circuits

pulmonary circuit - carries blood between the heart and lungs

right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium

• pulmonary arteries carry deoxygenated blood from the heart to the lungs

• pulmonary veins carry oxygenated blood from the lungs back to the heart

systemic circuit - carries blood between the heart and the rest of the body

left ventricle → aorta/arteries → body → veins/vena cava → right atrium

• aorta carries oxygenated blood from heart to body

• superior and inferior vena cava carry deoxygenated blood from the body back to the heart

sequence the direction of blood flow through the circulatory system

body → vena cava → right atrium → right ventricle → pulmonary valve → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle → aorta → body

recall the 7 major nutrient food groups

carbohydrates, lipids, proteins, vitamins, minerals, fibre, water,

describe the 3 major food groups of energy rich nutrients, their subunits and roles in the body

three major food groups that provide energy are carbohydrates, proteins, and lipids, and are made up of smaller units called subunits.

carbohydrates -

subunits - simple sugars (monosaccharides) e.g. glucose

main roles in body - main source of energy for cells

lipids -

subunits - fatty acids + glycerol

main roles in body - provides stored energy, helps insulate the body and protect organs

proteins -

subunits - amino acids

main roles in the body - used for growth and repair of cells and makes substances e.g. enzymes

recall and identify the major organs of the digestive system and describe their function

mouth → food is ingested, chewed, and broken into smaller pieces (physical digestion). the saliva begins chemical digestion of carbohydrates

stomach → churns and mixes food with stomach acid and enzymes, beginning the digestion of proteins

duodenum → the first part of the small intestine. it receives food from stomach and mixes it with digestive juices and bile to continue chemical digestion

small intestine → completes digestion and absorbs nutrients into bloodstream through villi

large intestine → absorbs water and some salts from undigested material, forming faeces for egestion

describe the 5 major processes of the digestive system (ingestion, peristalsis, digestion, absorption and egestion)

ingestion - food is taken into the body (eaten) via the mouth

peristalsis - when food travels along the digestive tube, smooth muscle tissue in the wall of the tube rhythmically contracts and pushes the food along the tube

digestion - food is broken down into smaller molecules. the digestive system breaks down food mechanically and chemically.

mechanical - food is physically broken down into smaller chunks

chemical - food molecules in chunks of food being broken down into smaller molecules, which can diffuse from the digestive system into the bloodstream and can be used by the cells of the body. this process is aided by enzymes (e.g. saliva added in mouth, gastric juices added in stomach, intestinal juices added in duodenum), which are chemicals that speed up reactions.

absorption - products of digestion (e.g. simple sugars, amino acids, fatty acids) can be absorbed across the wall of the small intestine. lining the wall are thousands of small finger-like projections called ‘villi’ (that increase the surface area greatly). water is also absorbed across the wall of the large intestine and rectum.

egestion - undigested food material, bacteria and other substances (e.g., left over digestive juices such as bile) form faeces that are stored temporarily in the rectum and then eliminated from the body via defecation.

describe mechanical and chemical digestion and identify examples of each

mechanical digestion - food is physically broken down into smaller parts without changing what the food is made out of e.g. chewing, stomach churning

chemical digestion - uses enzymes and digestive juices to break small pieces of macromolecules into their smaller units (e.g. stomach enzymes breaking down proteins, enzymes in small intestine digesting carbohydrates, proteins, and fats, carbs → glucose)

explain how absorption occurs in the small intestines, including the role of villi.

absorption - when small intestine takes digestive nutrients from food into the bloodstream

the inside of the small intestine is covered with millions of tiny, finger-like projections called villi.

• villi increase the surface area → more nutrients can be absorbed at once

• microvilli are even smaller projections on the surface of the cells that make up the villi, further increasing the surface area, allowing more nutrients to be absorbed

• contain many blood capillaries → quickly carries absorbed nutrients away and around body

• very thin walls → nutrients have a short distance to travel into the blood

• large surface area and good blood supply make absorption fast and efficient

small intestine → villi → microvilli → increased surface area → more nutrient absorption

explain how the digestive, respiratory and circulatory systems are interrelated in relation to cellular respiration

the digestive, respiratory and circulatory systems work together to provide cells with the substances they need for cellular respiration and remove the waste products produced.

the digestive system breaks down food into small molecules that the body can use. carbohydrates are digested into simple sugars like glucose, which is absorbed through the walls of the small intestine and enters the bloodstream.

the respiratory system brings oxygen into the body when we breathe. oxygen travels down the airways into the lungs and reaches the alveoli. it then diffuses from the alveoli into the surrounding blood capillaries.

the circulatory system connects these two systems by transporting the glucose from the digestive system and oxygen from the respiratory system through the blood to cells throughout the body. the cells use these substances in cellular respiration, which releases energy that cells need for activities such as movement, growth, repair and maintaining body functions.

cellular respiration also produces carbon dioxide as a waste product. the circulatory system carries the carbon dioxide away from the cells and transports it back to the lungs. it then diffuses from the blood into the alveoli and is removed from the body when we exhale.

what is the major role of the respiratory system?

THE MAJOR ROLE OF THE RESPIRATORY SYSTEM IS TO OBTAIN OXYGEN AND REMOVE CARBON DIOXIDE BY THE PROCESS OF BREATHING.

what is the major role of the circulatory system?

THE MAJOR ROLE OF THE CIRCULATORY SYSTEM IS TO TRANSPORT (CIRCULATE) NUTRIENTS, OXYGEN, WASTES AND HORMONES AROUND THE BODY.

what is the major role of the digestive system?

THE MAJOR ROLE OF THE DIGESTIVE SYSTEM IS TO BREAK DOWN COMPLEX FOOD MOLECULES INTO SIMPLE FOOD MOLECULES WHICH CAN BE ABSORBED INTO THE BLOODSTREAM AND USED BY THE BODY.

construct research questions for discrete data

does the (dependent variable) differ due to a change in the (independent variable) when the (controlled variables) are kept constant?

analyse quantitative data and interpret error bar overlap

what is the standard error of the mean?

SEM measures how far the calculated mean of the sample data is likely to be away from the true mean. it gives an idea of the variability of the individual measurements from the mean within a dataset. 

what does a small SEM mean?

a small standard error of the mean shows that many of the individual measurements were almost identical and that the dataset is more precise.

what does a large SEM mean?

a large standard error of the mean shows that at least some of the trials were very different from one another and that the dataset is less precise.

what does a very large SEM mean?

a very large standard error can indicate that there was a fault in the experimental procedure or inconsistent technique.

what happens when the error bars overlap on a graph?

the data likely does not have a statistical significance.

what happens when the error bars do not overlap on a graph?

a significance between the data sets is likely.

how do you measure error bars?

difference between top point of error bar and bottom point of error bar