This week in grade 9 science, we’ll start the process of developing your investigations into photosynthesis and respiration in Sansevieria trifasciata and Philodendron hastatum plants. The first steps of that process are a couple of preliminary experiment to establish an understanding of these essential processes.
The experiment below is the one we’ll be doing in class on Thursday and Friday of this week. Please make sure you’ve read all the way through the procedure before we start in the lab!
You will submit digital versions of the data tables and the analysis questions for homework after you’ve finished this experiment. You may send them via email.
Well, today was a little wacky, with no electricity or projector, class photographs in the middle of one class, and virtually no air circulating in my room to make for a hot hot hot day at school. Add in the noise and distraction of holding class in the courtyard, and we have….well, we have a bit of a mess.
Just so we’re all on the same page of the biology unit, I thought I’d summarize the key points from today’s lesson on biological molecules. Below are the finer points of the lesson.
The 3 major functions of all biological molecules
- Energy storage
- Source of energy
- chains of C, H, and O
- supply all energy in cells and food chains
- energy tends to be short-term energy (glycogen)
- simple sugars such as glucose may build more complex molecules
- some long chains of sugars, such as cellulose, are used for cellular structure
- most important biological molecule
- many functions in organisms:
- structural components (building blocks)
- made of chains of amino acids
- only 20 amino acids make all the 1000’s of proteins in the world
And finally, the slides from class…
Plants and animals are both eukaryotes, meaning they have distinct nuclei. (Bacteria, by contrast, are prokaryotes, which means they don’t have a nicely organized nucleus.)
Plants and animal cells have many other similarities: ribosomes, mitochondria, chromatin, cell membranes, smooth and rough endoplasmic reticula (ER), vacuoles, and Golgi complexes, among some other organelles we’re not studying in this unit. However, there are some fundamental differences between plants and animals on a cellular level:
- cell wall in plants
- chloroplasts (plastids) in plant cells
- large central vacuole in plant cells
- centrioles in animal cells
- some differences in the structure and function of the Golgi complexes
Watch this video for a nice summary, and please do click on the links he posts at the end for a deeper explanation of the topics he covers.
The following video is a bit more ‘scientific’ and uses some nice computer animation to tour plant cells. It’s worth a quick watch, too.
Now that we’ve spent some time getting to know our key vocabulary in the biology sequence, let’s start to delve a little deeper into the links and relationships among those words.
The Cell Theory is one of the foundational ideas behind all of biology, and it is something you must be familiar with before starting any future classes in bio. There are 3 main postulates to the Cell Theory, which I’ve listed below.
- All living things are made of cells.
- All cells come from pre-existing cells.
- The cell is the smallest unit of life.
Even though all living things are made of cells, not all cells are alike. Living organisms are classified into 5 kingdoms of life based on differences in their physiology and cell function. I think the link above and the image below nicely summarizes the way we classify living organisms.
In this unit we’ll look at one of the key distinctions among Earth organisms: the differences between plant and animal cells. The notes packet and diagrams you received in class contain the “official class notes” on this topic, so don’t lose them! You might also find the following items somewhat useful:
I post this picture because it eloquently relays a single, simple message: bad science.
How NOT to determine the mass of a sample.
How many things wrong can you identify in this photo? FYI, this is how one class left my room the other day.
Sorry I can’t be in class today, kids – I know you’re disappointed to have a cover teacher – so here’s the low-down on what you need to do while I’m out:
- Review the homework problems to make sure you have the correct answers and understand the process. The process is more important than the answers.
- Watch the dimensional analysis video linked here, then complete the quiz on that website to verify you understand how to do dimensional analysis.
- Go through my zombie presentation – yes, zombies do in fact know how to do dimensional analysis – and work all the practice problems in the presentation. You may do this with a partner if you want, and I’ll go over the answers with you next lesson.
- Review the document titled, “How to create graphs for science” and create a bullet-point list of all the required parts of a scientific graph. I’ll check this list as another homework check next lesson.
Here’s the zombie presentation:
Here’s the “How to create graphs for science” document in a viewing window:
Here are some tools to help you through the Measurements in Science homework assignment.
The video linked here methodically takes you through the dimensional analysis process, and it includes a quiz so that you can check your understanding.
This page has a lot of practice problems worked out for you, and it explains the process in easy-to-understand language.
Here’s the presentation we’ll use in class. Watch it. Study it. Master it.
Oh, and here’s another link that may be helpful. From Texas A+M University.
New Element Discovered!
Element 115, Ununpentium, has recently been confirmed through an extensive research process. Read all about it in this article from BBC Science and Environment.
Data tables are just that: tables of your results. Tables should be organized before you start your experiment, so that you can concentrate on your method instead of scrambling to organize your information while you work. Trust me on this: you will discover that your experiments go more smoothly if you come to class with your data tables set up, so that all you have to do is write the numbers in the right place.
Some rules for data tables included in your lab reports:
- Tables need a title! The title should identify what information is in the table.
- All columns should be labeled and include the units of measurement at the top.
- Use only numbers in the cells. (If you include the units as well, computers won’t read them as numbers, and they won’t be able to plot them on a graph for you.)
- Use the same number of decimal places in every measurement in a column.
- Center your numbers both vertically and horizontally to make the table easier to read.
Your first unit test is rapidly approaching! It will be a 5-part test on Friday 6 September (9A and 9C) and Monday 9 September (9B). Here are the 5 sections of the test:
- Common equipment – identify by name and use
- Lab safety rules – explain them
- Unit conversion and dimensional analysis – like the HW assignment
- Demonstrate use of graduated cylinder, electronic balance, and Bunsen burner
- Create a data table and a graph from given raw data
Please note that part 4 is a demonstration stage. Each student will be called to the central demo table, where I will observe your skills using a graduated cylinder, electronic balance, and Bunsen burner. You will have exactly 2 minutes to accomplish 3 tasks with these tools, so please make sure you are comfortable using them!
The test will be scored under Criterion C (Scientific Knowledge) and Criterion F (Attitudes in Science).