Practicing Circuits - P5

We're going to use the Circuit Builder to have a look at series and parallel circuits: http://phet.colorado.edu/en/simulation/circuit-construction-kit-ac-virtual-lab

Use the simulation to construct a series circuit with 2 batteries and 1 bulb. Look at how fast the electrons move and how bright the bulb is. Use the voltmeter and ammeter to measure voltage and current at different points in the circuit. Add another bulb and see how this changes things. Can you find out a rule for current and voltage in a series circuit? Search the web for what this might be and see if your circuit obeys these rules.

Now try a parallel circuit. See what happens if you make a circuit with one bulb, then add another bulb in parallel. What happens to the brightness of the bulb, and the current and voltage. Why is that? Add a few more bulbs in parallel to see if you can work out the rule for current and voltage in series and parallel.

Follow this Bitesize link to check if you are right: http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/electric_circuits/parallelandseriesrev1.shtml

Practicing Understanding of Circuits

Have a look at this link:

http://www.physicsclassroom.com/class/circuits/U9L3a.cfm

Look at the first 3 parts of the lesson: Journey of a Typical Electron, Resistance and Ohm's Law.
Complete the practice questions to check understanding.

If there are any parts that seem difficult or you don't understand, feel free to email questions. If the same questions keep coming up, I'll post an explanation on the blog.

Remember the address is westfieldacademyscience [at] gmail [dot] com

Revising with Past Paper Questions

The specification for the Biology units years 10 and 11 are studying are on this blog (B5 for year 11, B2 for year 10). Use the links at the side to find the spec for the unit you are currently studying. Have a read through and see where your strengths and weaknesses lie. Use this to decide the areas to revise.

There are many ways of finding past paper questions. One of the simplest is to type into Google: "B5 ocr past paper questions" or something similar.

Alternatively, look at the post from October called "General Revision sites". This has several links to different websites to help guide revision. Have a look around there for some past paper questions and bring what you do into school.

Good luck, and if you have any questions remember to send them to westfieldacademyscience [at] gmail [dot] com

B5 Specification

Module B5: Growth and Development

B5.1  How do organisms develop?

1.    recall that cells in multicellular organisms can be specialised to do particular jobs

2.    recall that groups of specialised cells are called tissues, and groups of tissues form organs

3.    recall that a fertilised egg cell (zygote) divides by mitosis to form an embryo

4.    recall that in a human embryo up to (and including) the eight cell stage, all the cells are  identical (embryonic stem cells) and could produce any type of cell required by the organism

5.    understand that after the eight cell stage, most of the embryo cells become specialised and  form different types of tissue

6.    understand that some cells (adult stem cells) remain unspecialised and can become  specialised at a later stage to become many, but not all, types of cell required by the organism

7.    understand that in plants, only cells within special regions called meristems are mitotically  active

8.    understand that the new cells produced from plant meristems are unspecialised and can develop into any kind of plant cell

9.    understand that unspecialised plant cells can become specialised to form different types of  tissue (including xylem and phloem) within organs (including flowers, leaves, stems and roots)

10.  understand that the presence of meristems (as sources of unspecialised cells) allows the  production of clones of a plant from cuttings, and that this may be done to reproduce a plant  with desirable features

11.  understand that a cut stem from a plant can develop roots and then grow into a complete  plant which is a clone of the parent, and that rooting can be promoted by the presence of plant  hormones (auxins)

12.  understand that the growth and development of plants is also affected by the environment, e.g. phototropism

13.  understand how phototropism increases the plant’s chance of survival

14.  explain phototropism in terms of the effect of light on the distribution of auxin in a shoot tip.

B5.2  How does an organism produce new cells?

1.      recall that cell division by mitosis produces two new cells that are genetically identical to each  other and to the parent cell

2.      describe the main processes of the cell cycle:

         a. cell growth during which:

•            numbers of organelles increase

•            the chromosomes are copied when the two strands of each DNA molecule  separate and new strands form alongside them

         b. mitosis during which:

•            copies of the chromosomes separate

•            the nucleus divides

     i      Candidates are not expected to recall intermediate stages of mitosis

3.      recall that meiosis is a type of cell division that produces gametes

4.      understand why, in meiosis, it is important that the cells produced only contain half the  chromosome number of the parent cell

5.    understand that a zygote contains a set of chromosomes from each parent.

B5.3  How do genes control growth and development within the cell?

1.      recall that DNA has a double helix structure

2.      recall that both strands of the DNA molecule are made up of four different bases which always  pair up in the same way: A with T, and C with G

3.      understand that the order of bases in a gene is the genetic code for the production of a protein

4.      explain how the order of bases in a gene is the code for building up amino acids in the correct order to make a particular protein

i      Candidates are not expected to recall details of nucleotide structure, transcription or translation

5.      recall that the genetic code is in the cell nucleus of animal and plant cells but proteins are produced in the cell cytoplasm

6.      understand that genes do not leave the nucleus but a copy of the gene (messenger RNA) is  produced to carry the genetic code to the cytoplasm

7.      understand that although all body cells in an organism contain the same genes, many genes  in a particular cell are not active (switched off) because the cell only produces the specific  proteins it needs

8.      understand that in specialised cells only the genes needed for the cell can be switched on, but  in embryonic stem cells any gene can be switched on during development to produce any type  of specialised cell

9.      understand that adult stem cells and embryonic stem cells have the potential to produce cells needed to replace damaged tissues

10.  understand that ethical decisions need to be taken when using embryonic stem cells and that  this work is subject to Government regulation

11.       understand that, in carefully controlled conditions of mammalian cloning, it is possible to reactivate (switch on) inactive genes in the nucleus of a body cell to form cells of all tissue types.

(c) OCR 2011 GCSE Science A