Biology GCSE Year 9 End of year

Name everything inside a animal cell

Name everything inside a animal cell

Cytoplasm, nucleus, ribosomes, mitochondria, cell membrane

Name everything inside a plant cell

Cytoplasm, nucleus, cell membrane, vacuole, chloroplast, mitochondria, ribosomes

Name everything inside a bacteria cell

cytoplasm, cell membrane, plasmids, ribosomes, cell wall, free floating DNA

Red Blood cell (specialised structure and function)

Specialised structure: No nucleus, flexible, large surface area

Function: carry a lot of oxygen, can pass through narrow capillaries.

Root hair cell (specialised structure and function)

Specialised structure: Large surface area,

Function: absorbs a lot of water

Sperm cell (specialised structure and function)

Specialised structure: long tail, pointed head, lots of mitochondria Function: streamlined to travel efficiently, mitochondria to release energy for movement.

Nerve cell (specialised structure and function)

Specialised structure: Long, many connections at the end, can carry electrical signals

Function: Can transfer electrical signals to many other cells.

Egg cell (specialised structure and function)

Specialised structure: only has half as much DNA as other cells, has a thick outer coating,

Function: Only one sperm can fertilise the egg, to make cells with the normal number of chromosomes.

How to calculate total magnification

Total magnification = objective lens magnification X eyepiece lens magnification

Label all the part of a microscope

1. body tube

2. Revolving nose piece

3. Low-power objective lens

4. medium power objective lens

5. stage

6. stage clips

7. Diaphragm

8. Light source

9. ocular lens/ eye piece

10. arm

11. rack stop

12. course adjustment knob

13. fine adjustment knob

14. base

Converting units

Unit name	Unit abbreviation	Fraction of a metre
Centimetre	cm	1/100
Milimetre	mm	1/1000
Micrometre	µm	1/1000000
Nanometre	nm	1/1000000000

cm - mm = x10

mm - µm = x1000

µm - nm = x1000

How to calculate image size

IAM

Optical, Transmittion EM, scanning EM

Microscope​	Visualize specimen using​	Max magnification​	Min. resolution (nm)​	Type of image seen​	Used to observe​
Optical​ ​ ​	​Visible light	​2000x	​200nm	​2D image or 3d is the living sample	​Living or dead samples
Transmission EM​	​Electron beam ​ ​	​2 000 000x	​0.1nm	​2D image black and white	​Dead samples- organelles inside cells
Scanning EM​ ​ ​	​Electron beam	​2 000 000x	​20nm	​3D image black and white	​Dead samples - surface of cells.

Define magnification

How many times bigger the image compared to the original. If the image gets to zoomed in it will go blurry

Define resolution

Minimal distance apart that 2 objects can be in order for them to appear separate.

Electron and light microscopes

Electron microscopes have much higher levels of magnification and resolution than light microscopes, so they show us much more details of the inside of cells. We can see the different organelles and learn more about them in the cell. Light microscopes have the advantage that they are cheaper, so we can buy them in school, and we can use them to look at living organisms.

How to answer a 6 mark question

6 mark question = When evaluating you write three paragraphs:

1st = 2 positive points

2nd paragraph - 2 negative points

3rd paragraph = justified conclusion. 

4 mark = no conclusion. 

4a Cells key words

Aseptic	Transferring bacteria without contamination
Binary fission	Asexual reproduction by doubling
Nutrient broth solution	A soup like solution with nutrients for bacteria
Agar	Jelly which you put in the petri dish which grows bacteria
Colony	A group of bacteria
Contaminate	To infect with bacteria
Disinfectant	A solution used to sterilise the surface
Antibiotics	A medication used to remove only bacteria
Petri dish	A circular shaped plastic container where agar jelly is placed.
Sterilise	To clean / remove all traces of bacteria.
Inoculating loop/ spreader	A wire loop use to transfer bacteria from one place to another.
Transfer	To move something from one place to another.
Incubate	Keep something at a certain temperature in a container/box
Anaerobic conditions	Without oxygen
Cross-sectional area	Area
πr2	Pi and radius squared
Zone of inhibition	Zone of bacteria which is unable to form
Standard form	10 to the power of x to make equations and answers easier to use

Chromosome facts

1. Inheritance is where genetics are passed on from your parents.

2. Sex cells are also called gametes.

3. The genetic information is contained in the nucleus of the cell.

4.   DNA is a double helix made up of two strands twisted into a helix

5. Humans have 46 chromosomes in a normal body cell.

6. he gene is the unit of inheritance.

How do genes work

Genes in side the nucleus contain DNA. They send messages into the cytoplasm for proteins to be synthesised at the ribsomes. These proteins allow the cells to become specialized to perform a specific function. This determines our physical characteristics. All our characteristics are product of our genes.

Explain this diagram

The normal body has 4 chromosomes in 2 pairs.

In the first stage of the cell cycle, a copy of each chromosome is made,

The cell is divided in two forms two daughter cells, each with a nucleus containing 4 chromosomes identical to the ones in the original parent cell.

Why are stem cells special

They are unspecialised, so they cannot do specific functions in the body

Where do you find stem cells

Mostly live in bone marrow

How can stem cells be used

To treat conditions in which bone marrow is damaged and is no longer able to produce healthy blood cells

Define mitosis

Mitosis is a process in reproduction where a single cell asexually divides into two genetically identical daughter cells.

Why are the cells produced identical?

If something goes wrong the cell won’t do what it is supposed to be and will create a tumour and give you cancer.

What would be a benefit of reproducing whole organisms in this way?

To have the same thing twice/ clone something. E.g If a chicken lays loads of eggs then you would want to have that same chicken to get way more eggs.

What are stem cells and why do we need them

Stem cells are undefrenciated/non-specialised which can change into any type of cell.

Stem cells can copy themselves and differentiate themselves (change)

 

Adult organisms have cells that have different jobs, These cells are specialised to carry out a certain function.

What is Mitosis

Mitosis is the process in reproduction which produced 2 genetically identical cells called daughter cells.

Name the 3 stages of Mitosis

There are 3 stages. In the first stage before a cell can divide it needs to increase the number of sub cellular structures like ribsomes and mitochondria. Then the DNA duplicates to form 2 copies of each chromosome and then spindle fibres pulls one set of chromosomes to each end of the cell. Then the nucleus divided. The last stage of mitosis the the cell membrane and the cytoplasm divide

Specialised animal cells and their functions

Red blood cell (imports oxygen)

Hair cell

nail cell

eye cell

root hair cell

Specialised plant cell and their functions

mineral lines

parastates cells (absorbs maximum amount of light)

Where are STEM cells

Adult stem cells location

Bone marrow

Skin

Brain

Eye

The Adult stem cells remain in a non-dividing state for years until activated by disease or tissue injury.

What is diffusion

The net movement of particles from a region where they are at a higher concentration to a lower concentration ( down the concentration gradient.) This is a passive process

Link diffustion to where it happens in the body

 Diffusion happens across membranes in lots of parts of your body. This is usually to move substances into the blood or remove substances from the blood. 

Urea diffuses out of the blood into the kidney tubes to make urine.

Carbon dioxide diffuses out of the lungs into the alveoli sacs to be exhaled.

Oxygen diffuses into the blood from the alveoli so it can be carried to the cells.

Feautures of a succesful exchange (MRS.L)

Moist

Rich blood supply (Maintains concentration gradient)

Short diffusion distance (Thin membrane)

Large surface area

The effectiveness of an exchange surface is improved by:

• Having a large surface area

• A thin membrane which ensures a short diffusion distance

• (in animals) an efficient blood supply

• (in animal gas exchange) being ventilated (good circulation of air)

When will diffusion become more difficult

 

As surface area to volume ratio decreases diffusion becomes more difficult.

Define osmosis

 The movement of water from a dilute solution to a more concentrated one through a partially permeable membrane. It can’t dilute water. This is a passive process so it does not require any energy

How to calculate the percentage change

Percentage change = (final value - original value / original value ) x100

Define active transport

Moving particles up the concentration gradient using energy This process requires energy

Why do cells that perform active transport have lots of mitochondria?

Mitochondria is the sight of respiration and respiration releases energy

Process of active transport

Molecules moving up the concentration gradient move by active transport. Substances such as glucose in the small intestine, K⁺ in the lung membranes and nitrates in the soil will be moved against the concentration gradient, to where they are already in higher concentration. This requires energy from respiration and can only happen through protein channels in the membrane. 

Where does active transport take place

Glucose from intestines into the blook. This is an active transport as it requires energy. Nitrates into roots from the soil. There is a higher concentration in the inside of the root of the plant. This is an active transport. You go from a less concentrated to a higher concentration

How are specialised cells adapted for active transport?

There would be lots of mitochondria to provide energy from anaerobic respiration. There needs to be lots of channel proteins.

How would cells adapt for diffusion and osmosis be specialised?

Large surface area to volume ratio. Provide by extensions to the cell membrane such as microvilli.

Compare diffusion, osmosis and active transport

Diffusion - high concentration to low concentration

diffusion and active transport - The transport of solutes

Diffusion and osmosis - Large surface area to volume ratio. Passive process

Osmosis - Water goes from a dilutes solution to a more concentrated one

Osmosis and active transport - They both need partially permeable membrane

Active transport - Mitochondria for respiration to release energy, goes from a low concentrated solution to a higher concentration.

All of them - Movement of particles, occurs in plants and animals

Word equation for photosynthesis

 water + Carbon Dioxide  ------- glucose + Oxygen

Symbol equation for photosynthesis

 6H₂O + 6CO₂  --------- C₆H₁₂O₆  +6O₂

2 more things needed for photosynthesis to occur

Energy + chlorophyll

Why would starch be found in leaves

glucose

How do we test for presence of starch

We use iodine to stain the leaf. If it is blue black it is positive

Types of leaf

Variegated	In all of the white part of the leaf it will turn a light browny/orange and the green part will turn blacky blue
Partially covered	The covered part goes a light browny orange and the not covered part turns blacky blue
Full light	Goes blacky blue

How many ways could you speed up this reaction?

• Increase temperature

• Increase light intensity

• Increase concentration of carbon dioxide

• Higher concentration of chlorophyll

What does describe and explain mean

 Explaining is when you say why something is happening. Describe is what you can physically see happen. (Appearance). Paint a picture in words.

Example of a describe and explain

Describe

Part 1 of the graph shows As the light intensity increases the rate of photosynthesis also increases. Part 2 of the graph shows As the light intensity increases the rate of photosynthesis stays the same.

Explain

The limiting factor in the first part of the graph is the light intensity. The second limiting factor in the graph are other external reactants which are required for photosynthesis such as temperature and concentration of carbon dioxide.

5 uses of glucose

1. Respiration - glucose is broken down to release energy

2. Synthesis - cellulose from cell wall and giant structures

3. Synthesis - animo acids glucose + nitrate is amino acids

4. Storage - fat/oil glucose is converted to glucose

5. Storage - starch insoluble easily broken down and doesn’t affect the movement of water

What is cellulose

Cellulose is the substance that makes up most of a plant's cell walls. Since it is made by all plants, it is probably the most abundant organic compound on Earth.

Evaluating data vocab

Accurate measurements	Closest to the true value
Precise measurements	These measurement are close together. (consistent results each time the activity is repeated)
Reproducible measurements	The same answer is obtained by a different person over and over again
Repeatable	The same answer is obtained by the same person over and over again.
Random error	An error that occurs without your control (e.g. loose count so you make up the answer.)
Systematic error	A error that is wrong with your system so you make the same error again and again
Anomalous value	Is a value that is outside the pattern of results. (one that sticks out)
Validity	The more i control the variable the more valid my data will be. (V for variable and V for Valid.)

Define respiration

Respiration is the process where all living things release energy from glucose.

word equation for aerobic respiration

Glucose + oxygen --> carbon dioxide + water

Where does respiration take place

Mitochondria

Why do cell respire

To release energy for :

1. Muscles to contract

2. Build larger molecules from smaller ones

3. In mammals and birds its needed to produce heat to keep them warm

Respiration chemical equation

 C₆H₁₂O₂ + 6O₂ ----> 6CO₂ + 6H₂O

Define anaerobic respiration

Respiration in the absence of oxygen

Partial breakdown of glucose without any oxygen to release a small amount of energy

GLUCOSE ---> LACTIC ACID

ONLY IN ANIMALS

It is the incomplete break down of glucose.

There is less energy released per glucose molecule during anaerobic respiration.

Anaerobic respiration takes place in the cytoplasm of the cell.

Lactic acid is a toxic waste product if it builds up in muscles it can cause muscle fatigue.

When might muscle cells need to do anaerobic respiration

you need to put in a lot of energy. E.G sprint to catch the train.

Why do we respire anaerobically

When we do strenuous exercise we may not be able to provide enough oxygen to our muscles for aerobic respiration to take place. The muscles still need energy to contract. If they have enough glucose they use anaerobic respiration to provide this energy so the exercise can continue for longer.

Can you now explain why holding your bags out at the start of the muscle caused the effects you noticed?

Anaerobic respiration is occurring because not enough oxygen was reaching the muscle cells to your arms which causes the build up of lactic acid then your get muscle fatigue.

Restricted blood flow

How is anaerobic respiration used in fungi

 Glucose ---> ethanol + carbon dioxide (+ energy) only happens in yeast

Compare Aerobic and anaerobic respiration

Aerobic	anaerobic
Occurs in Mitochondria	Occurs in cytoplasm
Complete breakdown of glucose	Incomplete breakdown of glucose
Carbon dioxide and water are waste products	Lactic acid is a waste product
Releases large amounts of energy slowly	Releases smaller amounts of energy quickly
Glucose is the reactant	Glucose is the reactant
Requires oxygen	Doesn't require oxygen

What increases when you start exercising

Your breathing deeper

Your body temperature increases

Your breathing is more rapid

Body aches

Your hearts beats faster

Blood going to your muscles

Define lactic acid

The build us of products from a chemical reaction that happens when you resipre anaerobically. Toxic product. Acid built up in the muscles causes by the incomplete oxidation of glucose

Muscle fatigue

The lactic acid builds up in the muscles making the muscles feel tired/ fatigue

Oxygen debt

When we have to give the necessary amount of oxygen to the muscles after exercising to remove any remaining lactic acid. The amount of oxygen needed to break down lactic acid after exercise is finished.

Metabolism

Metabolism is the sum of all the reactions in a cell or the body