Biology unit 2 Cards

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  • Created by: James
  • Created on: 21-01-13 19:05

Animal and plant Cells

Animal and plant share some common structures: they both have

  • A nucleus- This controls all activity in the cell and also contains the genetic information.
  • Cytoplasm- This is where most/all the chemical reactions take place.
  • A cell membrane- This controls substances coming in and out of the cell
  • Mitochondria- This is where most of the energy during respiration is released.
  • Ribosomes- This is where protein synthesis (making of protein) takes place.

A plant cell also has:

  • Cell wall- This supports the cell. Made of cellulose. (keeps it rigid)
  • Chloroplasts- These contain a green substance, called chlorophyll, which absorb light.
  • Vacuole- This is made of cell sap. It keeps the cells rigid.


  • Has a cell wall
  • The genes are not in a distinct nucleus
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Specialised cells

Cells may be specialised to carry out a particular function.

  • Root hair cell- Has a large surface area to absorb water and minerals. Close to xylem.
  • Palisade cell- Column shaped cells can be packed tightly together. A lot of chloroplasts.
  • Sperm cell- Big nucleus. A tail to swim. A lot of mitochondria for energy.
  • Fat cell- Not much cytoplasm. Fat cells can expand.
  • Cone from the human eye- A lot of mitochondria in mid section to provide energy.
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Diffusion is the net movement of particles from one area of high concentration to an area of lower concentration.

Factors affecting diffusion

  • Surface area- The larger the surface area, the faster the rate of diffusion.
  • Temperature- The higher the temperature, the faster the rate of diffusion.
  • Distance- The shorter the distance, the faster the rate of diffusion.
  • Concentration gradient- Steep=big diffusion.   Shallow=small diffusion
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Tissues, Organs and Organ systems

Animal organs

  • Muscular tissue, which can contract to bring about movement.
  • Glandular tissue, which can produces substances such as enzymes and hormones
  • Epithelial tissue, which covers some parts of the body


  • Contains muscular tissues to churn the food
  • Contains glandular tissues to produces digestive juices
  • Contains epithelial tissues to cover the inside and outside of the stomach.

The digestive system

  • Glands, such as the pancrease and salivary glands, which produce digestive juices
  • The stomach and small intestines, where digestion occurs.
  • The liver, which produces bile
  • The small intestine, where absorption of soluble food occurs.
  • The large intestine, where water is absorbed from the undigest food.
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Carbon dioxide + Water -----------> Glucose + Oxygen

Limiting Factors

  • Temperature- The higher the temp, the faster the rate of reaction (movement increases) however at a certain temperature enzymes denature therefore reaction slows.
  • Light intensity- Light is the energy used to convert the carbon dioxide and water into glucose
  • Carbon dioxide- Carbon dioxide is needed to make glucose.

How is glucose used?

  • The glucose may be converted into starch for storage
  • Plant cells use some of the glucose during photosynthesis.
  • To produce cellulose (for the cell wall)
  • To produce proteins (need nitrate ions, that are absorbed from the soil)
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Collection of quantitative data

Random Sampling

  • Generate random numbers using a computer (or something similiar)
  • Use these to determine the co-ordinates of the collection point. 
  • This eliminates bias, that may occur by the inestigator.
  • Ensures that results are valid
  • Investigate the population of the species in the quadrat. (Absence, Percentage cover or Number foud)

Transects (Used when there are changes in distributions of organism. If there is a change in neighbouring habitat)


  • Choose the start and end positions. (Determine the direction and length of transect)
  • Lay down a tape or string to mark out transect
  • Sample the organisms along the line
  • Perform further parallel transects to ensure results are reliable. (note factors influencing
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Factors effecting enzymes

  • Temperature- The higher the temp, the faster the reaction (particles move) however enzymes denature at certain temp. (Enzymes lose their 3D shape, active site lost)
  • pH- Enzymes are prone to pH changes. Some work better in different pH. It denatures due to the acidic/alkaline changing its structure.


Enzymes make it more effecient to remove stains from clothes. Also lower washing temperatures can be used which saves energy. However if the clothes are not fully rinsed,protease enzymes may remain in the clithing. (They digest proteins in the skin) This can lead to irritations,allergies and dermatitis.


Enzymes enable industrial reacitons to take place at lower temps. Heat is expensive, there it would be cheaper. However they are susceptible to pH and temp changes. (money needed in monitoring and controlling conditions, which can be expensive)

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Respiration in cells take place aerobically or anaerobically.

Aerobic respiration

Glucose reacts with oxygen, producing carbon dioxide and water as waste products. (Occurs in animals and PLANTS)

Glucose + Oxygen ------------. Water + Carbon dioxide (+ energy)

Anaerobic respiration

  • During exercise, if insufficent oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
  • It is the incomplete breakdown of glucose and produces lactic acid.
  • Less energy is released.
  • Lactic acid is poisonous. Our bodies can only tolerate small amounts.
  • Muscles become fatigued.
  • Oxygen gets rid of lactic acid (We breathe heavily to oxidise the lactic acid)
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Respiration and exercise

Respiration during exercise

  • Muscles need energy to contract.
  • When we exercise muscles contract more quickly and with more force. 
  • This requires more energy (which means more glucose and oxygen)
  • Also, more carbon dioxide is created, which needs to be removed.

Changes during exercise

  • The rate and depth of breathing increases. 
  • The heart rate increases. (more oxygen carried to muscles)
  • All of these changes increase the blood flow to the muscles and so increase the supply of sugar and oxygen and increases the rate of removal of carbon dioxide.
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Learn how to spell 'Mitosis'


  • Body cells divide to make new cells
  • Before a cell divides, it produces new copies of the chromosomes in the nucleus. This means that when division takes place, two genetically indentical daughter cells formed.


  • In early development there are a lot of stem cells. 
  • They can become any type of cell needed
  • In many animals they become specialised very early in life.
  • They become specialised for a particular job/
  • When they specialise, they can only reproduce into the same type of cell.
  • Research of stem cells in medical treatment. (Learn/make up some ethical arguements)
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  • Chromosomes double
  • The cells divide into two
  • They divide again straight away.
  • This means there are 4 un-indetical daughter cells, with only 50% of the original chromosomes.


  • Fusion of gametes. (50% of chromosomes come from one parent, the other comes from the other.)
  • Meiosis causes variations of chromosomes each individual gamete has.
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Key words

  • Allele- A version of a particular gene.
  • Homozygous- When you inherit the same genes, from parents
  • Hetrozygous- When you inherit different genes, from parents.
  • Recessive- Characteristic will only show up if the alleles are the same.
  • Dominant- Characteristic will still show, even if there is one allele/
  • Genotype- The genetic make up of an organism
  • Phenotype- The characteristic shown through

Cystic Fibrosis

Is a disorder of cell membranes. Causes thick, sticky mucus to accumulate in the lungs and digestive system. This causes lung infections, problems with breathing, digestion and absorption. Caused by recessive allele.


Extra fingers/toes. Caused by dominant gene. Only one copy needed.

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Punnet Square

Write out phenotype- Which parents are affected, which aren't?

Genotype- The letter associated. Is it recessive or dominant?

Draw the gametes

Make the square. (describe what results are. Who is affected? Percentage affected etc...)

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They are from a long time ago. They show that organisms were a lot simplie. That things have evolved. Can see that they have evolved from common ancestor (due to traits shared). However fossil records may be incomplete.


Occurs due to changes to environment (geological time). New predators, new diseases, new competitors, catastrophic events (asteroids) or if they are unable to adapt.


Geographic isolation seperates the species. (eg, spliting of Pangaea). The species will adapt to new enviroment. Genetic variations may cause some members of species to be better suited to environment. Natural selection, best pass their genes on. When the species meet again, they will be too different that successful interbreeding is no longer possible.

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  • Spelling of mitosis and meiosis matters.
  • On longer mark questions which asks way is this better, you have to compare. (for example don't say "item A is expensive" instead say "Item A costs more than Item B")
  • Draw the punnet square, then explain all possible outcomes.
  • Explain means to talk about why something is happening. 
  • Describe means to talk about what you see.
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