Yr 12 Biology Taster lesson Objectives: To gain an understanding of the structure of the new A level course To have a go at an A level practical Locate the summer task

Feedback and Expectations GCSE WWW & EBI A-level expectations

Your handbook and transition guide can be found on the W Drive.  Science  KS5  Biology  Yr 12  Yr 12 Taster Lesson

Overview 4hrs contact plus 4hrs private study per week. No assessed coursework. 18x Core practical activities (CPACs) that make up a practical endorsement. Regular assessment. 3x 2 hour exam papers (2019). 4x topics each year (see handbook).

FAQ Course structure Expectations 4hrs contact/4hrs private Textbook sign up A-level booklet (W-drive) 18x Core practicals Lab book Assessment after 4 weeks, mid topic and end of topic Interventions by classroom teacher plus Yr 12 JLE, Yr 13 MLW GCSE Grade B (Below that historically struggle) Double scientists can catch up over summer (W-drive) SNAB resources, support and structure Possibility of workshops, summer schools, work exp., trips etc Revision guides via SQUID

Summer task Challenge Complete the baseline assessment and bring in to your first lesson back after summer

Gametes, fertilisation and gene expression in plants. We need to be able to dissect, make observations, identify and label plant structures in a number of lessons in year 12. Plant fertilisation, growth of pollen tubes and gene expression. Importance of plants Seed bank Attenborough

Flower Dissection Pg 113 and 133 Dissect a flowering plant. Identify, draw and label Sepals, Petals, Stamen and Carpels. Take a carpel and dissect further to identify the style, ovary and if possible the ovules EXTENSION If time observe the growth of pollen tubes from pollen grains in the samples provided under a microscope. http://www.saps.org.uk/secondary/teaching-resources/1357-a-level-set-practicals-producing-a-scientific-drawing

Dissection and Scientific Drawing Learning outcomes   You will: Observe the structure of a flower Observe, dissect and record the floral parts of that flower Prepare a longitudinal section of a flower Produce an annotated scientific drawing of the longitudinal section of the flower Understand how the structure of the flower is adapted to its function.

Dissection and Scientific Drawing Health and Safety   CLEAPSS Student Safety Sheet 74 provides information about assessing the risk posed by plant material.  Many plants contain toxins. To minimize any potential risk, inform your teacher if you are aware of allergies to a particular plant so that it can be avoided. The pollen of some lilies stains clothing. Wear a lab coat to protect your clothes. Take care when using sharp instruments such as single-edged (safety) razor blades, scalpels, scissors and mounted needles and follow the instructions for their safe use that have been given to you by your teacher. When drawing it is important to take regular breaks to avoid eye strain and damage to the wrist and back. A short rest from drawing every half hour is a good idea.

Generalised structure of a flower

Parts of an Alstroemeria flower

Cutting a longitudinal section through a flower

Common drawing errors

Common drawing errors

Scientific drawing

Fully annotated scientific drawing

SEM of pollen grains and pollen tubes SEM of pollen grains and pollen tubes. Whilst carrying out your flower dissection try to observe and draw pollen tubes growing from pollen grains http://www.saps.org.uk/secondary/teaching-resources/222-student-sheet-4-pollen-tube-growth

How many parts can you identify from memory?

How many parts can you identify from memory?

Pollen Tube Growth Investigations Are the pollen grains all the same? Make a sketch of half a dozen pollen grains. Work out a way of estimating the size of a pollen grain. Compare your results with those obtained by other members of the class. Leave the pollen grains for one hour, but look at them down the microscope from time to time. Describe and measure any changes which you see. Compare your pollen grains with those set up by other members of the class. Design a way of measuring the rate at which the pollen tubes grow. Record your results. Do all pollen tubes grow at the same rate? Go back to the flowers. Measure the distance from the stigma to the bottom of the ovary in ten different flowers. Compare the distance with the length of your longest pollen tube. Is it a fair comparison? Why do you need to measure more than one flower and more than one pollen tube?

Pollination When a pollen grain is released from an anther, it is partially dehydrated.  If it lands on the surface of a stigma of the same flower (self-compatible) or of a different flower of the same species (self-incompatible), it rehydrates.  Some species produce flavinols in both the pollen and anther, which is necessary for growth.  Mutant maize plants that are deficient in the enzyme that synthesises flavinols are self sterile.  Addition of flavinols restores the ability of the pollen to grow and fertilize the ovules of the female plant. As pollen tubes grow, callose plugs are produced close to the aperture of the pollen grain, so the cytoplasm becomes concentrated towards the growing tip