Studying towards a GCSE in Biology equips with you with some of the fundamental details and knowledge that you will need to be able to contemplate how life works.
With topics spanning from diet and nutrition to food chains and living organisms to reproduction, each lesson is taught with everyday relevance so students will learn about the role of Biology and how it affects not only their lives but life in general day in, day out.
Because it is known as the Science of Life, Biology is relevant to all students and is a key transferrable subject. Offered by multiple exam boards, the syllabi all have the same purpose, which is to teach pupils about their place within the world, raise awareness and to build a passion for Biology.
Studying The Sciences At GCSE Level
GCSE stands for General Certificate of Secondary Education, and is a certification traditionally taken by those aged around sixteen years-old.
One very important thing to note as you enter your first or second year of GCSE is that this course has undergone many changes in the last couple of years. This means that the structure of courses may be different than before, as well as how you are assessed.
However, it is not just the grading in general that has been adapted over the years. The Sciences in particular have recently undergone some specific changes that might affect you. Keep reading to find out more.
Most GCSE pupils will be familiar with the historical grading system, which awarded marks ranging from A*-G. However, a new grade system is currently being phased into the UK education system whereby pupils are marked against a 9-1 system instead.
This new grading method will have been applied for the first time on this year’s Year 11 students who studied English Language, English Literature and Mathematics, with the remaining subjects being changed over the course of the next couple of years.
Ofqual, the exams watchdog, has advised educators not to make direct comparisons between the two because the boundaries do differ and it could be misleading for pupils.
Moreover, if you have already selected your GCSE options, you will already understand that Science courses are marked differently now than before.
Whereas in previous years you would have studied Biology, Chemistry and Physics as part of a Double or Triple Science award, you now choose one Core Science, which will be your academic focus during the course of the two years, and then select an additional subject, which will have a more vocational aspect.
You get separate grades for each Science studied now which allows students more opportunities to excel in Science.
GCSE Biology Subjects At A Glance
For some, a Biology GCSE might be their last formal study of the Science yet for others, it could be the start of continued studies within the field, leading the way to a profession within the Live Sciences sector. Either way, Biology provides the foundations for understanding the natural world and how Science is continuously changing our lives.
The primary topics covered by the AQA GCSE Biology, one of the more common specifications, are Keeping Healthy, Nerves and Hormones, The Use and Abuse of Drugs, Interdependence and Adaptation, Energy and Biomass in Food Chains, Waste Materials from Plants and Animals, Genetic Variation and its Control, Evolution, Cells and Simple Cell Transport, Tissues, Organs and Organ Systems, Photosynthesis, Organisms and their Environment, Proteins - their Functions and Uses, Aerobic and Anaerobic Respiration, Cell Division and Inheritance, Speciation, Movement of Molecules In and Out of Cells, Transport Systems in Plants and Animals, Homeostasis and Humans and their Environment.
Reproduction In Humans
One of the topics covered by Biology at GCSE Level is Reproduction, which examines the human body, in particular the sexual organs, and how women and men reproduce.
While you may have been taught about the human body during sex education in earlier years or even during discussions with your parents, this more advanced course will explain a little more about the functions of the male and female sex organs, as well as exploring hormones, puberty and how a fetus grows.
Before moving onto how the respective sex organs work together to create life, we first of all need to have an understanding of how each works independently.
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Many vertebrate animals reproduce in much the same way as humans do: the male and female of any given species combine sperm with ova (eggs). The fertilised egg is then incubated in the mother’s uterus. There, it evolves and develops until it is ready to live independent of its mother.
The zygote represents a combination of both parents’ alleles and contains all of the genetic information for the production of a new being.
Obviously, there being two sets of genes, only half of them can express; some become recessive and others dominant. We can see the activity of those genes without any type of scientific equipment: in the colour of skin and hair, in the colour and shape of the eyes, the length of limbs and so on.
Plants, single-celled organisms and invertebrates all have different means of reproduction.
Unlike reproduction in humans and other organisms requiring two gametes, this type of reproduction results in the offspring being clones of the parent.
Mitosis is a form of cell division which results in an exact copy of the parent cell.
Unlike human reproduction, which employs a process called meiosis to create gametes that would later fuse to become a zygote, asexual reproduction uses mitosis to create clones.
Examples of organisms that practise asexual reproduction are:
- fungi, in their production of spores
- bacteria and other single-celled organisms
- Runners, or stolons, permit strawberries to reproduce asexually
- Daffodils produce bulbils along their stems that, when planted, will result in a new plant.
- Potatoes also reproduce with no sexual congress.
Asexual reproduction has several advantages, among them, being the time that it takes to reproduce.
Sexual reproduction requires a compatible male and female to mate. Before that can happen, other factors must line up: a suitable mate must be found; for some species, a ritual then ensues. Finally, the conception must not be impeded by either environmental factors or disease.
Asexual reproduction is much faster in that no search for a compatible mate is needed, nor is there as much time involved to produce offspring.
However, environmental factors such as chemical exposures – to pesticides or herbicides, for example, as well as extreme temperatures do affect an organism’s ability to clone itself.
Populations of asexual organisms can grow very rapidly if the conditions are right.
On the other hand, seeing as such creatures are cloned from their parent, there is no genetic diversity and the risk for the entire population to succumb, to disease or some other external factor, is much greater.
Genetics & Inheritance
You will already know that you inherit genes and characteristics from your biological parents, yet what this topic does is exposes just how our DNA structure is made up and how one of each pair of chromosomes comes from your mother and father.
While you inherit equal amounts of chromosomes from both parents, this does not mean to say that the physical or emotional characteristics you display and feel will be split half and half. One child may take after their father more than their mother in a variety of ways and siblings will often develop their own unique features.
After learning about the structure of DNA, including base pairs, you will turn your attention to alleles. These are different versions of the same gene and are referred to as either dominant or recessive.
Finally, you will explore the different types of cell division and the stages that they go through. You will discover that Mitosis, for example, produces two identical cells with the same number of chromosomes as in the original cell. Meanwhile, Meiosis, which produces gametes, creates four genetically different haploid cells. The latter is called a reduction division because the chromosome number is halved from diploid to haploid.
GCSE Biology Evolution
Evolution describes how particular or accidental gene changes have occurred over time to give the living organism characteristics they need to survive better.
During this topic, you will learn about natural selection and how this causes genetic variation, including how bacteria can become resistant to certain antibiotics. Your teacher will explain how the increasing strains of antibiotics due to misuse have resulted in more infections that are difficult to control. You will thus be made aware of the wider dangers of misusing antibiotics or not completing a full course.
Indeed, misusing antibiotics includes not taking all of the medicine your doctor prescribes. Here’s why that is a dangerous practice:
Antibiotic medications are targeted to defeat bacterias’ life cycle – the cloning and reproducing of those organisms, either by rendering them unable to reproduce or by killing them outright.
Let’s suppose you are giving a 10-day supply of antibiotics. That should represent the amount of time needed for the chemicals in the medicine to stifle the bacteria’s reproductive capability. Unable to clone themselves, the bacterial colony dies off.
However, you feel better after taking medicine for only 7 days, so you stop taking it.
Of the entire bacterial colony, some have thus far survived the onslaught and, now that they are no longer targeted, they are free to reproduce.
Remember that asexual reproduction is very efficient and very fast.
It is possible that the medicine in question has altered those cells’ genetic structure, permitting them to evolve defence mechanisms against the chemicals in medicine that target them. And then, as those microbes get passed on...
That is why health experts warn about superbugs that no current antibiotic can conquer, that loom ever greater on the horizon as one of our most serious health concerns.
In addition to learning in depth about that topic, this fascinating module will cover selective breeding, i.e. causing changes to genes on purpose to improve crops or livestock. As a direct result of human intervention, selective breeding causes new varieties of species to be born and is therefore referred to by some as artificial selection.
With a focus on continuous and discontinuous variation, you will also find out what types of characteristics fall into which category as well as exploring the effects of gene mutation.
Living organisms are categorised according to their characteristics. During this part of the Biology course, you will find out about the different kingdoms that exist on our planet and how species are classified within them.
Vertebrates, which are animals with backbones, include amphibians, birds, bony fish, mammals and reptiles. Invertebrates, on the other hand, do not have backbones and include annelids, arthropods, molluscs and nematodes.
Flowering plants make up two groups: monocotyledons and eudicotyledons. The first includes plants such as grasses, orchids and palms whilst the latter consists of buttercups, dandelions and oak trees.
Keys are used to identify and classify the different species, asking questions that can only have one of two possible answers. These dichotomous keys are usually displayed in the form of a branching diagram, similar to those you see in magazine quizzes (i.e. "Are you X or are you Y?" style).
As your course develops, you may begin to learn about the variety of living organisms and the levels at which they are organised.
King Phillip Called On Five Great Soldiers
This is a mnemonic – a memory device that can help you remember Carl Linnaeus’ classification system. Thanks to him, all living beings are classed in order of: kingdom, phylum, class, order, family, genus and species.
For humans, the classification would be:
- Animal (kingdom)
- vertebrate (phylum)
- mammal (class)
- omnivore (order)
- hominidae (family)
- homo (genus)
- sapiens (species).
Naturally, when referring to humans in scientific circles, only the last two classifications are given. This is known as binomial designation.
This binomial system permits a clear distinction between species that may belong to the same family and genus but, through migration and subsequent evolution, have had to adapt to a different environment.
Perhaps the best-known example of such would be Darwin’s finches: (approximately) 15 different species whose beaks especially had adapted visibly and physically to their specific region.
In fact, so divergent are they that, today, they are recognised under different genera altogether!
Nutrition, Digestion And Excretion
In spite of our consuming a variety of foods, they mostly boil down to three categories, each with a specific function.
Proteins ensure the repair and growth of cells. Eggs, meats, cheese, beans and seeds contain a lot of protein.
Our carbohydrates come from two major sources: sugars and starches. Examples of carbohydrates from sugar include fruits and fruit juices, sweets and fizzy drinks. Potatoes, rice, bread, pasta and cereals top the list of starchy foods that are loaded with carbs.
Carbohydrates are necessary for energy and to make glucose, the sugar vital to our bodies’ continued balance and function.
Ideally, our lipids, or fats, should come from fatty fish, plant oils, and nuts and seeds. You can also find a high percentage of fats in butter and margarine, processed meats and even in unprocessed meat.
Although proteins, fats and carbohydrates are necessary for cellular respiration – the way cells energise through oxidation, carbs provide that process with the lion’s share of glucose.
That is why fad diets that restrict carbohydrate intake are not necessarily the best ways to ensure optimal health!
When learning about diets, you will start to understand more about the different types of foods and their functions. For instance, you will get a deeper understanding than given here about carbohydrates, proteins and lipids and their functions in relation to the human body.
You will then discover sources of vitamins and how deficiencies in these areas can affect us too.
Whilst encouraging you to seek out your specific energy requirements and how to maintain a healthy, balanced diet, you will additionally be taught how other influences can affect our diets including pregnancy, activity levels and illness.
When it comes to learning about our digestive system, you will explore how each of the food types, once ingested, are broken down and absorbed and how the chewed ball of food then moves through the body before being excreted. In addition, you will be told how certain foods impact on our teeth and cause decay.
Throughout our bodies, multiple chemical reactions are constantly and simultaneously taking place but one of our bodies’ most complex processes is absorbing nutrition.
From the second we put a bite of food into our mouths and start chewing, enzymes swing into action to start breaking down complex molecules so that they will be small enough, by the time they get to our small intestines, to be absorbed.
Enzymes are proteins that speed up the chemical breakdown of foods into digestible particles.
Let’s say jacket potatoes are your favourite veg; you insist on having one every day. Come tea time, you can hardly wait to dig in to its creamy, soft interior...
The enzyme amylase, so prevalent in our mouths, immediately begins the breakdown of the starch your potato is so rich in. That starch will undergo further molecular separation in your gut until it is rendered into maltose, a sugar molecule small enough to pass through the intestinal wall.
And then, hitching a ride in the bloodstream, maltose is taken to the liver for further processing and eventual consumption as energy.
Specific enzymes fulfil specific tasks and are located in exacting regions in the body.
You will not necessarily need to know the name of every enzyme and what it works on but it is always a good idea to get a complete a picture as possible, don’t you think?
Taking that idea further: havng a list of key terminology can be very useful when you come to revise for your exam, besides making use of the abbreviated list below, be sure to consult glossaries, perhaps on Bitesize, for each topic that comes up.
Glossary of Select Biology Terms
No doubt, you already have a long list of terminology related to biological functions and processes. In case you don’t, or if your list is incomplete, we present some of the more obscure terms that you must know in order to score well on your exam.
Allele: any of the alternative forms of the same gene
Amino Acids: essential for building proteins; key elements are carbon, hydrogen, oxygen and nitrogen.
Binomial: having two names. It is standard practice to name every organism for its genus and its species, in that order.
Chromosome: the structure made from DNA that codes for all of the characteristics of an organism.
Cytoplasm: the living substance in a cell that surrounds its nucleus.
Gamete: a sex cell; in males they are sperm; in females, ova (eggs)
Gene: the basic unit of genetic information; organisms inherit genes from their parents
Genome: the complete set of DNA found in an organism.
Meiosis: division in a cell; a diploid becomes a haploid
Mitosis: cloning; a process in which a produced cell is identical to the parent cell.
Mutation: a random or spontaneous change in the structure of a gene, chromosome, or number of chromosomes
Organism: any living entity including plants, animals and microbes
Pathogen: a microorganism that causes disease
Phenotype: visible characteristics resulted from genetic expression
Phylum: a main taxonomic category; it falls under ‘kingdom’ but ahead of ‘class’.
Protein synthesis: occurring in the cells’ ribosomes (the area of the cell where protein synthesis happens), it the production of proteins from amino acids.
Speciation: formations of new species as a result of evolution.
Villi: Tentacle-like projections in the wall of the small intestine that expand the surface area designed for food absorption. Each villum (singular of villi) is, in turn, covered in microvilli.