IB Science - Free response question strategies

Quality points are awarded for

Clarity of expression:

clearly written responses- the examiner can read the answer once and get the meaning.  It is not the handwriting that counts, it is the clarity of your answer and ideas.  Be sure to write a logical progression of ideas by  planning your answers so that you write in a clear logical order in each section.  Avoid jumping back and forth in sequences.  Drawings should not have label lines that cross, tables of comparison should be constructed with comparative feature is shown with each item to be compared.

full and complete attempts- all three sections are addressed and clearly indicated ie. 4a, 4b, 4c.  DO NOT MIX SECTIONS FROM DIFFERENT QUESTIONS!

Structure of answer:

logical linking of ideas within at least 2 sections of the question- this is usually seen in the higher point value sections, not in drawings or lists.  These links should be clear ideas, using additional material supporting your explanations or  discussions so you really need to know the meaty details of the syllabus.

 

IB Science - Multiple choice questions

Multiple choice questions come up on practically every Group 4 IB subject - be it physics, chemistry, biology, ecosystems, sports sciences and so on....... Hence thats a lot of marks given as a gift - if you know the right techniques ;)!

Firstly, get familiar with the several types of questions:

Sequence type questions

Sequences are best addressed by reading down the first item in the sequence to eliminate the choices and then proceeding across the sequences until you have only one choice remaining.

For example:

What is the correct order of taxonomic categories from largest to smallest?

1. kingdom--> order--> class--> phylum --> species


2. species--> order--> phylum--> kingdom--> class


3. kingdom--> phylum--> class--> order--> species


4. species--> order--> class--> phylum--> kingdom

Now you have only to choose between the two.  Next look down the second item of the sequence to eliminate the false choice.

1. kingdom--> order--> class--> phylum --> species


2. 
   


3. kingdom--> phylum--> class--> order--> species


4. 
   

Finally you have the answer!

1. 
   


2. kingdom--> phylum--> class--> order--> species


3. 
   

Table type questions

Frequently, it is easier to read down one of the columns and eliminate the items that are not correct.

The questions usually are comparative of structures or functions.

Which of the following shows the correct features of arteries and veins?

artery vein a thick elastic wall thin inelastic wall b thin elastic wall thick inelastic wall c thin inelastic wall thick elastic wall d thick inelastic wall thin elastic wall
so if you read down you can eliminate: artery vein a thick elastic wall thin inelastic wall b thin elastic wall thick inelastic wall c
d and finally:
artery vein
a thick elastic wall thin inelastic wall

Genetics questions

Various type of genetic crosses, pedigrees will be shown here.  How to identify genotypes and inheritance patterns will be illustrated.

• Crosses


• Monohybrid ( single trait)


• Dihybrid (two traits)


• Non-Mendelian crosses


• Sex-linked


• blood types


• codominant- dihybrid


• Polygenic ( multiple genes)

Data based question strategies

See the more detailed post on data response questions.

Graphical presentation questions

See the more detailed post on how to interpret graphs.

I, II, III- type

These questions give you  a combination of three or four options.  The best way to attack is to eliminate the options (I, II, III, IV) you know (feel) are incorrect and then eliminate any answers with those options.  Be ready to accept all the options!

Which of the following are required for proper blood clotting?
I.       Release of thrombokinase from platelets and damaged tissues
II.     Damage to leucocytes
III.   Prothrombin in the plasma
IV.    Fibrinogen in the plasma
A. I only
B. III and IV only
C. I, III and IVonly
D. I, II, III and IV

Since leucocytes are not involved in blood clotting, this option is not required so any answer choice with II is wrong- eliminate D.

Since thrombokinase, prothrombin and fibrinogen are all needed, then C is correct answer.

Image interpretation

The IB will present diagrams, drawings and electronmicrographs in questions.  You will be asked to interpret the image for knowledge about specific details:

-- structure and function of organelles

-mitochondria

-- structure and function of  cells- acini, epithelial (microvilli)

-- prokaryotic vs eukaryotic cells

-- plant vs animal cells

You should be able to accurately measure and calculate the magnification or actual size given relevant information.

Other images to interpret:

-- organs or systems- structure and function

-- food chains, pyramids, cycles

-- metabolic pathways and processes

-- DNA profiles, karyotypes, pedigrees

 

IB Biology - Quick Study Tips

A brief glossary to trigger your memory

-A-

-ASE = enzymes (lactase acts on lactose, lipase acts on lipids)

Axons carry impulse Away from the cell body.

Arteries carry blood Away from the heart.

Active TransPort needs ATP,

Active transport goes  Against the grAdient

Alpha cells in pancreas produce glucAgon to increAse blood sugar levels

"Animals are made of cells" said T Schwann (swans are animals)

Anion is A Negative Ion

-B-

B lymphocytes clone to make plasma cells which make antiBodies against specific antigens


-C-

Cations - Ca is a + ion

Constriction by Circular muscles Contracting - in the arteries when in the Cold, in the iris when in the dark

C and G always have 3 (cytosine and guanine pair up with 3 H bonds in DNA and RNA)

-D-

Diffusion is always Down a concentration graDient

-G-

GA for Gene HbA, GAG in DNA sense strand, GAG in mRNA,  Glutamic Acid in Haemoglobin - for Sickle Cell anaemia.  (see STUV)

-Gen = creation of  (glycogen, fibrinongen, oestrogen)

GlucagON turns sugar ON (increase blood sugar levels by breaking down glycogen to glucose)

-H-

sHort day plants are inHibited by active Pfar-red


-I-



I D-  Insulin Dependent is Diabetes type I

I I- Insulin Immune causes Diabetes type II


-In = proteins (insulin, haemoglobin, pepsin)


INsulin makes glucose go IN to cells (liver and muscles to be stored as glycogen or to be used in respiration)-

Insulin made by Beta cells- (think IB!)

 

-L-

Ligaments hold bones to bones in joints- think about knee injuries

Lagging strand has 3 G's, is 3 prime to 5 prime strand,  has 3 DNA enzymes (DNA polymerase I and  III,  DNA ligase + RNA primase) and replicates DNA in fragments

-M-

Matrix in the Mitochondrion- (see S for stroma)

-O-

-ONE = steroid hormones (progesterone, oestrogen, testosterone)

-OSE = sugars (glucose, sucrose, amylose or starch, cellulose)

Oval window in ear is shaped like a stirrup

Oxygen is made early in phOtosynthesis- photolysis of water in early in LDR and is used late in respiratiOn- electron acceptor at end of electron transport chain

-P-

Photosynthate in the Phloem

Photosynthesis uses NADP/ NAPH+H         (not NAD / NADH+H)

Progesterone : Pro = in favour of , gester = pregnancy, -one = steroid hormone

-R-

Ringer - characteristics of living things (Reproduction, Irritibilty, Nutrition, Growth, Excretion, Respiration)

BohR shift- low pH curves shifts to the Right

-S-

SenSe strand is like the meSSage used to make the  the rubber stamp which is like the antisense strand that is replicated to make the SenSe strand which is the meSSage used to make the rubber stamp to make the meSSage......

STUV- for Sickle Cell anaemia

Gene Hb S, GTG in DNA sense strand, GUG in mRNA, Valine in         Haemoglobin S  (seeGA)

STroma in a chloroplaST- (see M for matrix)

-T-

Tendons hold muscles to bone- think Achilles tendon in ankle.

Transcripition of the anTisense strand of DNA

anTicodon is on t- RNA- same order as anTisense strand of DNA

-V-

Veins have Valves

-W-

WXYZ-

Water in the XYlem (sounds like Zylem)

-Y-

thYmine and cYtosine are pYrimidines (so is uracil)

-2-

2  genetically identical cells made by Mitosis (mi two  sis)  

-3-

3 H bonds between cytosine and guanine (3 rhymes with C and G)

3 g's in LAGGING strand, 3 DNA enzymes work on the 3 prime to 5 prime of lagging strand in  DNA replication making Okazaki fragments

-5-

5 prime to 3 prime direction for replication of new DNA strand and transcription of RNA andtranslation of mRNA to polypeptide.  This is because the 5 prime carbon ( 5 like fingers on your hand) of nucleotides has  phosphates  which bond to the 3 prime carbon of next nucleotide (3 like the 3 bumps on your elbow)

-23-

23 is haploid number of HUMAN gametes (sperm and ovum have one set of chromosomes)


-46-

46 is diploid number of HUMAN cells (somatic cells have two sets of chromsomes)- other organisms have different numbers of chromosomes

IB Biology - Data based question strategies

Data-based questions come up on Paper 2 and 3 all the time. Make sure you study the graph or information given at the start of the question.

Interpretation of graphs & Relationships

Being able to interpret graphs is a skill that you will need for the exams.

The first step is to identify the scales and axes, looking at the units.  Are the scales linear or log scales?    You must show the units in your answers.

After this, pay attention to the lines and relationship of the data:

Are the lines linear (straight?) what is the slope (gradient)?  Positive or negative?  Do the lines cross?  At what point?

Are the lines non-linear?  What is the relationship-  exponential, plateau, inverse, S cureve, hyperbolic, root function?

If you're finding difficulties in doing this, check out how to establish a relationship from a graph.

Sometimes the data does not show a simple relationship.  For example, here are a collection of past paper data base questions.

Calculations

Be sure to give the units in your answers as shown in the graphs and tables.  This may seem complicated but just copy everything after the "/" on the axes or in the heading of tables.  You will lose 1 mark for omitting the units! No reason to throw away a mark when PhewStressit is given to you!