Sections 1 and 2 to e)

Question 1

Main groups:

Answer 1

Plants
Animals
Fungi
Bacteria
Protoctists
Viruses

Question 2

Characteristics of living things

Answer 2

Movement 
Reproduction
Sensitivity- respond to surroundings 
Growth 
Respiration - release of energy from food 
Excretion- getting rid of waste 
Nutrition
Control - internal conditions

Question 3

Plants

Answer 3

• multicellular organisms
• cells contain chloroplasts
• they photosynthesise
• cells have cellulose cell walls
• store carbohydrates as starch or sucrose

Examples- flowering plants (cereal ((maize))
Herbaceous legumes (peas or beans)

Question 4

Animals

Answer 4

• multicellular organisms
• cells contain no chloroplasts
• don’t photosynthesis
• no cell walls
• normally have nervous coordination
• able to move from one place to another
• often store carbohydrates as glycogen

Examples-

• mammals (humans)
• insects (housefly or mosquito)

Question 5

Fungi

Answer 5

• organisms
• don’t photosynthesise
• body usually organised into mycelium made from thread-like structures called hyphae
• many contain nuclei
• -some are single celled, their cells have walls made of chitin
• • feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products- saprotrophic nutrition
• -may store carbohydrate as glycogen

Examples - mucor, typical fungal hyphal structure
Yeast- single celled

Question 6

Bacteria

Answer 6

• microscopic single-celled organisms
• cell wall, cell membrane, cytoplasm and plasmids
• no nucleus
• contain a circular chromosome of DNA
• some carry out out photosynthesis
• mostly feed off other living or dead organisms

Examples-
Lactobacillus Bulgaricus- rod shaped bacterium used in the production of yoghurt from milk
Pneumoccus- spherical bacterium that acts as the pathogen called pneumonia

Question 7

Proctoctists

Answer 7

• microscopic single-called organisms

Examples
-amoeba - live in pond water, have features like an animal cell
-Chlorella, have chloroplasts and are more like plants
Pathogenic example is plasmodium- responsible for causing malaria

Question 8

Viruses -

Answer 8

• small particles
• smaller than bacteria
• parasitic
• can reproduce only inside living cells
• infect every type of living organism
• they have a wide variety of shapes and sizes
• no cellular structure
• have a protein coat
• contain one type of nucleic acid, either DNA or RNA

Examples-
Tobacco mosaic virus-
Causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts
Influenza virus that causes 'flu'
HIV virus that causes AIDS

Question 9

Pathogen

Answer 9

Organisms that cause disease
They include some fungi, proctosits, bacteria and viruses

Protoctist: plasmodium, which causes malaria
Bacterium: pneumococcus, which cause pneumonia
Viruses: influenza virus (causes ‘flu’) and HIV (which causes AIDS)

Question 10

Organelles

Answer 10

Tiny structures within cells - only seen through a powerful microscope

Question 11

Cell

Answer 11

They are specialised to carry out a particular function, so their structures can vary

For example- in humans, red blood cells are specialised for carrying oxygen and white blood cells are specialised for defending the body against disease.

Question 12

Tissues

Answer 12

It is a group of similar cells that work together to carry out a particular function
For example- xylem tissue (for transporting water and mineral salts) and phloem tissue (for transporting sucrose and amino acids)
A tissue can contain more than one cell type.

Question 13

Organs

Answer 13

They work together to form organ systems. Each system does a different job.

For example, in mammals, the digestive system is made up of organs including the stomach, intestines, pancreas and liver

Question 14

2.3 and 2.4- Cell structure - nucleus

Answer 14

An organelle which contains the genetic material that controls the cell’s activities. It is surrounded by its own membrane.

Question 15

Cytoplasm

Answer 15

A gel-like substance where most of the cell’s chemical reactions happens. It contains enzymes which control these reactions.

Question 16

Cell membrane

Answer 16

This membrane forms the outer surface of the cell and controls the substances that go in and out.

Question 17

Cell wall

Answer 17

A rigid structure made of cellulose, which surrounds the cell membrane. It supports the cell and strengthens it.

Question 18

Chloroplast

Answer 18

Photosynthesise, which makes food for the plant, happens here. Chloroplasts contains a green substance called chlorophyll, which is used in photosynthesis.

Question 19

Vacuole

Answer 19

A large organelle that contains cell sap (a weak solution of sugars and salts.) it helps to support the cell.

Question 20

2.4- Compare plant and animal cells

Answer 20

• Both have a nucleus, mitrochondria, cytoplasm, cell membrane and ribosomes
• Plant cells have a cell wall, chloroplasts and a vacuole as well.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/cells/cells1.shtml

Question 21

C) biological molecules

2.5 - what are the chemical elements present in carbohydrates, proteins and lipids (fats and oils)

Answer 21

• Carbohydrates - carbon, hydrogen and oxygen
• Lipids - carbon hydrogen and oxygen
• Proteins- carbon, hydrogen, oxygen and nitrogen

https://www.bbc.co.uk/education/guides/z8wsgk7/revision

Question 22

What are the structures of carbohydrates, proteins and lipids.

Answer 22

They are all large molecules made up from smaller base units:
Starch and glycogen from simple sugars
protein from amino acids
lipids from fatty acids and glycerol

https: //www.bbc.co.uk/education/guides/z8wsgk7/revision/2
https: //www.bbc.co.uk/education/guides/z8wsgk7/revision/3
https: //www.bbc.co.uk/education/guides/z8wsgk7/revision/4

Question 23

Tests for glucose and starch

Answer 23

Glucose- Add benedict’s solution to it, and heated for around 5 minutes in a water bath, if glucose is present then the benedicts solution will go from blue to brick red/orange.
Starch- Add iodine solution to something and if it contains starch it will go bluey/black in colour

Question 24

Understand that enzymes are biological cayalysts in metabolic reactions

Answer 24

An enzyme is a protein that functions as a biological catalyst – a substance that speeds up a chemical reaction without being changed by/used up in the reaction.
They are in complex shapes with their place where molecules can fit being called the active site. The enzyme works through the lock and key model, the shape of its active site, matches the shape of its substrate. Enzymes are specific they can only catalyse those which are complementary in shape to its active site.

Question 25

How the functioning of enzymes can be changed by changes in temperature, including changes due to the change in active site.

Answer 25

Changing temperature changes the rate of ebzyme-catlysed reaction. A higher temperature increases the rate until a certain point (Enzymes work best at an optimum temperature of 37 degrees celsius) but if the temperature is to get higher than 37 this can cause changes in shape to the enzymes active site (above 37 enzyme bonds can break when weakened by being too hot), becoming denatured therefore it can no longer work as a biological catalyst.

Question 26

Experiment to investigate how change in temperatyre can affect an enzyme’s activity.

Answer 26

• page 6 in CGP revision guide
• enzyme catalyses the breakdown of hydrogen peroxide into water and oxygen
• easy to collect oxygn produced and measure how much is given off in a set period of time
• series of experiments each with a water bath at different temperatures, to see how different temperaure affects the activity of catalase.
• (control variables page 83)

Question 27

d) Movement of substances into and out of cells

Diffusion-

Answer 27

The random net movement of particles from a high to low concentration

Question 28

Osmosis

Answer 28

Net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Question 29

active transport

Answer 29

movement of particles against a concentration gradeitn (i.e. from an area of lower concentration to an area of higher concentration) using energy released during respiration.

Question 30

Movement of substances into and out of cells can be by diffusion, osmosis and active transport

Answer 30

Water moves into and outo cells by osmosis

Question 31

Factors which affect the rate of movement of substances into and out of cells

Answer 31

surface area to volume ratio- higher rate of diffusion, osmosis and active transport in cells with a larger surface area to volume ratio. for example … (page 10 CGP revision guide)
temperature- as the particles in a substance get warmer, they have more energy– so they move faster. As temperatyres increases, substances move in and out of cells faster.
concentration gradient- substances move in and out of a cell faster if there’s a big difference in concentration between inside and outside of the cell (see page 7). Onlu affects rate of diffusion and osmosis NOT ACTIVE TRANSPORT.

Question 32

Experiments to investigate diffusion and osmosis using living and non living systems
page 9 CGP

Answer 32

Diffusion in a non living system -

• make up some agar jelly with some phenophthalein (PH indicator) and dillute sodium hydroxide
• This will make the jelly a pink shade
• Then add some hydrochloric acid to a beaker, and cut out a few cubes from the jelly and put them into the beaker of acid
• if you leave the cubes for a while they should turn colourless as the acid diffuses into the agar jelly and neutralises the sodium hydroxide.

Question 33

Experiments cont -
Osmosis in living system- potato cylinders
page 9 CGP

Answer 33

• cut up a potato into identical cylinders
• get some beakers with different sugar solutions in them
• one should be pure water, another should be a very concentrated sugar solution, and others with concentrations in between
• measure the length of the cylinder
• leave a few in each beaker for half an hour or so
• take them out after the time and measure their lengths again
• if the cyclinders have drawn in water by osmosis then they will be a bit longer.
• if water has been drawn out then it will of shrunk.

Question 34

Osmosis in non living systems- visking tubing

page 9 CGP

Answer 34

• tie a piece of wire around one end of some visking tube
• put a glass tube in the other end- fix the tubing around it with wire
• pour some sugar solution down the glass tube into the visking tube
• put the visking tubing in a beaker of pure water
• measure where the sugar solution comes up to on the glass tube
• leave the tubing overnight, then meausre where the liquid is in the glass tube.
• • water should be drawn into the visking tubing by osmosis and this will force liquid up the glass tube

Question 35

e) nutrition
flowering plants
- process of photosynethsis and important in the conversion of light energy to chemical energy

Answer 35

Photosynthesis is the process that produces ‘food’ in plants, this ‘food’ it produces is glucose. It happens in the leaves of all green plants- largely what the leaves are for. Photosynethsis happens inside the chlorplasts, which are found in leaf cells and in other green parts of a plant. Chloroplasts contain a pigment called chlorophyll, which absorbs sunlight and uses the energy to convert carbon dioxide and water into glucose. Oxygen is also produced

Question 36

Photosynethisis equation

Answer 36

carbon dioxide + water –(sunlight)– glucose and oxygen

6CO2 + 6H20 –(chlorophyll)– C6H12O6 + 6O2

Question 37

how carbon dioxide concentration, light intensity and temperature affect rate of photosynethsis

Answer 37

• Chlorophyll uses light energy to perform photosynthesis. It can only do it as quickly as the light energy is arriving.
• if the light intensity increases, then the rate of photosynthesis will increase steadily, only up to a certain point.
• beyond that point it will make no difference because then it’ll be either the temperature or the CO2 levels which is now the limiting factor.
• too little carbon dioxide also slows it down
• increasing the concentration of CO2 will only increase the rate of photosynethsis up to a point. After this it will not longer be the limiting factor.
• as long as light and CO2, are in plentiful supply then the factor limiting photosynthesis must be temperature.
• temperature affects the rate of photosynethsis - because it affects the enzymes involved
• as the temp increases, so does the rate of photosynthesis (up to a point)
• if the temp is toohigh (over about 45) the plant’s enzyme will be denatured, rate of photosynthesis rapidly decreases.

Question 38

Structure of the leaf

Answer 38

Page 19 CGP book

Question 39

How leaves are adapted for photosynethsis

Answer 39

• Leaves are broad — LSA exposed to light
• Most of chloroplasts are found in the palisade layer– near the top, can get the most light
• Upper epidermis is transparent, light can pass through it to the palisade layer
• network of vascular bundles - these are the transport vessels xylem and phloem. Deliver water and other nutrients to every part of the leaf and take away glucose produced by photosynthesis. Also help to support the leaf structure
• Waxy cutile helps to reduce water loss by evaporation
• Adapations of leaf for efficient gas exchange – also make photosynthesis more efficient – for example lower surface is full of little holes called stomata, let CO2 diffuse directly into the leaf.

Question 40

Plants require mineral ions for growth–

Answer 40

• • Nitrates (contain nitrogen) - for making amino acids and proteins. Also needed for cell growth. If it doesn’t get enough nitrates it will be stunted and will have yellow older leaves.
• • Phosphates (contain phosphurus) - for making DNA and cell membrane and they’re needed for respiration and growth Plants without enough of them have poor root growth and purple older leaves

– Potassium - help the enzymes needed for photosynthesis and respiration. IF there’s not enough potassium in the soil, plants have poor flower and fruit growth and discoloured leaves

– Magnesium - Required for making chlorophyll ( needed for photosynthesis, plants without enough will have yellow leaves.

Question 41

Experiments to investigate photosynthesis

Answer 41

How to test a leaf for starch-

• kill leaf by dunking in boiling water to stop chemical reactions happening
• put the leaf in s boiling tube with some ethanol and heat tube in a water bath (gets rid of chlorphyll so turns the leaf a pale, white-ish colour)
• rinse the leaf in cold water and add a few drops of iodine solution
• if starch is present it will turn a bluey/black colour

– it shows whether photosynthesis is taking place.

Question 42

Show how chlorphyll is needed for photosynthesis experiment

Answer 42

Chlorphyll-

• you can show that it is needed for photosynthesis using variegated (green and white) leaves. Only the green parts of the leaves contain chlorphyll.
  1) take a variegated leaf from a plant that’s been exposed to light for a bit. Recore which bits are green and white bits are white.
  2) test the leaves for starch (card before)- only bits which are green will turn bluey/black in colour when iodine is added
  3) this suggests that only the bits that contain chlorophyll are able to photosynthesise and produce starch.

Question 43

Carbon dioxide experiment test- photosynthesis

Answer 43

• using a bell jar, put in soda lime and plant and shine a light into it from the outside
  1) the soda lime will absorb CO2 from out of the air in the jar
  2) if you leave the plant in the jar for a while, then test it for starch it will not go blue/black in colour
  3) this shows that no starch has been made in the leaf, which means that Co2 is needed for photosynthesis

Question 44

dentify sources and desrcibe functions of carbohydrates, protein, lipid (fats and oils), vitamins A, C and D, and the mineral ions calcium and iron, water and dietary fibre as components of the diet

Answer 44

Carbohydrates- found in pasta, rice and sugar – provide energy

lipids - found in butter, oily fish – provides energy, act as an energy store and provide insulation

Vitamins:

• Vitamins A - liver, helps to improve vision and keep your skin and hair healthy
• Vitamin C- oranges, helps to prevent scurvy
• Vitamin D- eggs, needed for calcium absorption

Mineral Irons:

• Calcium- milk, cheese - makes bones and teeth stronger
• Iron - red meat, needed to make haemoglobin for healthy blood.

Water- food and drink, just about every bodily function – need a constant supply to replace water lost through urinating, breathing and sweating.

Dietary Fibre- wholemeal bread, aids the movement of food through the gut

Question 45

describe the structures of the human alimentary canal and describe the functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas

Answer 45

Structure on page 16 CGP
functions:
- Mouth- salivary glands in the mouth produce amylase enzyme in the saliva, teeth break down food mechanically.

• oesophagus - carry food, liquids and saliva from the mouth to the stomach, its a muscular tube which connects the mouth and the stomach.

stomach- pummels food with its muscular wall, produces protease enzyme (pepsin), produces hydrochloric acid to kill bacteria and to give the right PH for the protease enzyme to work ( PH 2- acidic)

small intestine- produces protease, amylase and lipase enzymes to complete digestion. where the nutrients are absorbed out of the alimentary canal into the body.

large intestine- where excess water is absorbed from the food

pancreas- produces protease, amylase and lipase enzymes. then releases them into small intestine.

Question 46

understand the processes of ingestion, digestion, absoprtion, assimilation and egestion

Answer 46

• Ingestion- putting food (or drink) into your mouth
• Digestion- after you’ve ingested something, you need to digest it. digestion is the break down of large insoluble molecules into small soluble molecules. your body has mechanical and chemical ways of digesting food:
• • mechanical– teeth and stomach muscles
• • chemical – digestive enzymes
• Absorption - it is the process of moving molecules through your walls of the intestine into the blood. Digested food molecules are absorbed into the small intestine – water is mainly absorbed in the large intestine.
• Assimilation - when digested molecules have been absorbed, they’re moved into body cells. the digested molecules then become part of the cells. For example amino acids (from digested proteins) are assimilated, theyre used by cells to make cellular proteins.
• Egestion - not everything that you can ingest can be digested. All of the undigested stuff forms faeces, which are no use to our body and get rid of them through expelling them through the anus.

Question 47

How and why food is moved through the gut by peristalsis?

Answer 47

1) there’s muscular tissue all the way down the alimentary canal
2) its job is to squeeze balls of food (boluses) through your gut – otherwise it would get clogged up
3) this squeezing action, which is waves of circular muscle contractions, is called peristalsis.

Question 48

Understand the role of digestive enzymes

Answer 48

1) starch, protein and fats are big molecules, too big to pass through the walls of the digestive system. They’re also insoluble.
2) sugars, amino acids, glyceol and fatty acids are much smaller molecules, they’re soluble and pass easily throught the walls of the digestive system
3) digestive enzymes break down the BIG molecules into the smaller ones

Amylase converts starch into maltose
… maltase converts maltose into glucose

proteases convert proteins into amino acids

lipases convert lipids into glycerol and fatty acids

Question 49

Understand that bile is produced by the liver and stored in the gall bladder, and understand the role of bile in neutralising stomach acid and emulsifying lipids.

Answer 49

1) Bile is produced in the liver, stored in the gall bladder before it’s released into the small intestine
2) the hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is alkaline… neutralises the acid and makes the conditions alkaline … these conditions are ones which the enzymes work best in.
3) Bile also emulsifies fats… breaks fat into tiny droplets… gives them a bigger surface area of fat for the enzyme lipase to work on — makes digestion faster

Question 50

Structure of the villus and explain how this helps absorption of the products of digestion in the small intestine.

Answer 50

Villi in the small intestine help with absorption

1) the small intestine is adapted for absorption of food
2) its very long (normally around 8m or so), so there’s time to break down and absorb all the food before it reaches the end
3) really big surface area for absorption, because the walls of the small intestine are covered in millions and millions of tiny little projections called villi.
4) each cell on the surface of a villus also has it owns microvilli - little projections that increase the surface area even more
5) villi have a single permeable layer of surface cells and a very good blood supply to assist quick absorption.