Life Processes at the Cellular Level | NCEA Level 2 Biology | StudyTime NZ
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Life Processes at the Cellular Level | NCEA Level 2 Biology | StudyTime NZ

– Kia ora guys,
(gentle electronic music) welcome to StudyTime’s
Level Two Strategy Video for life processes at the cellular level. I’m McKenzie. – And I’m Hattie. So a lot of students find
the Standard really tricky, because there’s just a
lot of content in it, and a lot of questions will mush together a lot of the different
concepts into one answer. So it’s really important
that you’re able to identify the key ideas behind each question, and break it down into those. Yeah, so, the two big overarching ideas within the Standard really just is, life processes and
different biological ideas. So, let’s get into it. – First, let’s run
through the main processes you’ll be asked about in this external. Which are: photosynthesis,
respiration, and cell division, which can further be broken down into DNA replication and then mitosis. The key thing with all these processes, is that you need to understand where in the cell they happen,
what all the stages are, maybe not in full detail,
but definitely a general idea of what each step involves, and also how they all interact to come together to form life. – So understanding the three processes that Hattie mentioned earlier, we’ll start with photosynthesis. Now bear in mind, this only
happens in plant cells, and specifically in chloroplasts, which is an organelle
unique to plant cells. Now an understanding of the relationship between how the cells absorb sunlight, it can be really handy to know
a cross section of a leaf, and understanding the
different layers within it. So, in particular, you’d
be wanting to discuss something like the palisade layer, that has a lot of cells with
a high amount of chloroplasts. Also, a common question can be either labeling or
creating your own diagram of a chloroplast, so bear
this in mind as well. Secondly, is respiration, and so a common mistake that students make is thinking that this only
happens in animal cells. This is wrong, because respiration
is the process by which we are creating energy that the body uses, so this actually has to happen in both plant and animal cells, and as we know, it occurs
in the mitochondria. Thirdly, we want to
understand the relationship between mitosis and DNA replication. These are not the same thing. DNA replication has to occur
before mitosis can happen, so that both daughter cells are diploid, and can carry out regular cell function. If you’re feeling a
little bit unsure of this, it can be really handy as well to understand the cell cycle as a whole, and the reasons why mitosis might occur. – As well as these three main processes, there are also five other areas that can be interwoven with
them to form an NCEA question. There’s firstly the movement of materials, so that’s diffusion,
osmosis, active transport. Secondly enzyme activity. Thirdly, factors affecting
the life processes, so that’s things like
temperature, PH, sunlight. Fourthly, the purposes of
each of these processes, and fifthly, the reasons for the
similarities and differences between particular cells. For example, size and shape of cells, or the number of organelles in them. An NCEA question won’t just
focus on one of these things, it will be several jumbled together. So for example, you won’t just be asked to talk about the purpose
of photosynthesis, you’ll be asked to talk about
how photosynthesis happens, what it’s for, and how
enzymes can affect it. – So for some strategies for success, let’s discuss some of the questions that students are a little
bit less confident with. So, one of these is the
structure of organelles, so, why is it that they
take the shape that they do? So, if we’re discussing
something like mitochondria, we would be discussing the
outer and inner membrane, and how the inner membrane
is folded to create cristae to ultimately increase surface area. Alternatively, if we’re talking about this in regards to chloroplasts, we can be talking about grana, which is our thylakoid stacks, and how this increases
surface area as well. Now, another thing to bear in mind is the shape of the overall organalle, so a lot of them are longer,
and again, you guessed it, it’s to increase surface area,
so more amount of material can diffuse into the
organelle at a given time. Now, another question that a lot of students
sometimes struggle with, is the reasons for organelles arrangement. Now what this really means is, why is it that do some
cells have higher amounts of mitochondria or chloroplasts
compared to others. So for mitochondria, it
might be something like a muscle cell as opposed to a fat cell. So our muscle cells, because
they’re far more active, and they require far more energy, will have a higher amount of
mitochondria than a fat cell. If we’re taking this for plants, we can be discussing our
cross section of our leaf, and we’ll say things like the palisade layer of our leaf section has a higher amount of chloroplasts than the spongy mesophyll section, that has a considerably lower amount, cause that’s really just catching what the palisade layer missed. Lastly, we need to consider things like the factors affecting
our rate of reactions, our rate of the processes happening. So, we can kind of think of this as it boils down to enzyme activity, but there are also things like
heat, and light intensity, and substrate availability
which affect this rate. In regards to mitosis, we also need to consider
things that affect life, so these might be things like, the amount of nutrients that we can get, the kind of cells that are available, so if an organism isn’t
getting the right nutrients and things it needs, the
rate of growth of a cell is going to be considerably lower. – If you’re aiming for those E grades, it’s really important to understand how the questions are generally
structured in the exam. Generally, there’ll be about
three to four bullet points. The first one will be asking
you to define a key term, which is more of an Achieve skill, the second will be an
explanation question, which is really asking you how to relate what you’ve
just said in the definition to the context in front of you. That can go up to about a Merit. And the third and fourth
will be about discussing how that’s actually relevant, how a bunch of factors play into it, that’s when you get
those Excellence marks. If there are more than
one discussion point, it’s really important that
you answer all of those to an equal quality,
because Excellence answers need to show comprehensive understanding of every single part of the question, so try and devote approximately equal time and page space to both of them. Even though there’s only
one definition bullet point, every time you introduce a new term you should be defining it. That said, don’t just try and define all the terms you’ve learned
over the course of the year, make sure you’re only defining
terms that are relevant to the actual situation in front of you in the resource material. Finally, NCEA actually sometimes gives you some wee hints about
how to get a good mark, and students often miss these. For example, in the 2015 paper, there was a question about a hogchoker, which is a type of salt water fish, asking you why the concentration
of salt in the water would increase the hogchoker’s
oxygen consumption. Now, in the question, NCEA had actually bolded
the word “active”, meaning active transport. And we should know that active transport uses energy, and to use that energy, to get that energy, respiration
needs to take place. So oxygen needs to be taken in. If you actually spotted
that keyword and used it, you’d be able to understand
how the ideas linked together, how if the hogchoker needed
to actively transport salt out of its cells, then it would need to take in
oxygen to gain that energy. – So guys, this has been StudyTime’s Level Two Strategy Video for life processes at the cellular level. We’ve covered a lot, but we haven’t quite covered everything, and as always, we recommend
that you guys check out three to four years worth
of past exam papers, so you get an idea for the format, and the kinds of questions
you’re going to be asked. We also recommend you check out the StudyTime walkthrough guides, they’re available for free online, or to purchase and print
with next-day delivery, and they’re designed to walk you through everything you need to
know before the exam. So, good luck! (gentle acoustic outro)

14 thoughts on “Life Processes at the Cellular Level | NCEA Level 2 Biology | StudyTime NZ

  1. This vid is so good when you are revising, these girls clearly knows what they are talking about.
    If ur reading this, all the best luck for your tuesday's bio exam. <3

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