life science essays grade 10

List of Life Sciences essays for Grade 10, 11 and 12 (South Africa)

Life Sciences essays for Grade 1 0, 11 and 12 (South Africa):

Table of Contents

List of Life Sciences essays for Grade 10, 11 and 12

NEPHRON ESSAY

Essay Question: Write a short essay explaining the homeostatic functioning of the nephron if a person is suffering from dehydration

Life Sciences essays for Grade 10, 11 and 12

When the water content of the body drops below normal, the following happens

• the osmotic potential of the blood increases √  
• which stimulates the osmoreceptors in the hypothalamus √
• which produces ADH
• to transmit impulses to the pituitary gland (hypophysis) √
• to release more ADH √ in to the blood
• ADH is transported by bloodstream to the kidney √ where this hormone increases the permeability √ of the walls of the distal convoluted tubule and collecting duct √
• more water √ is re-absorbed from the filtrate √
• and small amount of concentrated urine √ is excreted
• the adrenal gland √ secrete aldosterone √ which cause sodium ions √ to be actively √ pumped out of the filtrate √ in the ascending limb of loop of Henle √ in to the tissue fluid of the kidney medulla √
• this creates a low water potential √ and water moves by passive osmosis √  from the collecting tubule √  in to the tissue fluid of the medulla √ from where it is absorbed in to the blood capillaries √

ECOUTOURISM ESSAY

Essay Question: Write a mini essay on ecotourism in South Africa using the following guideline

• Brief explanation of what ecotourism entails,
• Long term sustainability and Possible threat to Ecotourism  
• Ecotourism is mainly inclined to promote environmental awareness and instil asense of appreciation of natural formations and beauty.
• It makes people respect the existence of other living organisms (fauna and flora) that shares the resources of the planet earth
• Its main clients are people who are interested in preserving the environment.
• A potential ecotourist prefers to spend his/her holidays in a natural environment to experience and be part of the environment
• They like to visit and spend time in quiet natural settings such as unspoiled beaches, river mouths, waterfalls, wet lands with lush green forests, gorges,mountains etc.
• Always prefer to use eco-friendly mode of transport to cause less pollution and damage to fauna and flora
• Encourages people to consume naturally grown, fresh produce from the area
• Greater emphasis is placed on the well-being of local people and constantly look for ways and means to contribute towards the local economy
• Eco-friendly accommodation is provided for visitors to minimise the possible human impact on the surrounding area
• Renewable energy is utilised wherever possible

Long term sustainability

Educate the local population about the importance of conserving the natural resources.

• The involvement of the local community should be prioritised.•
• Active participation generates income for local communities. e.g. selling composts, organic food products.
•  Job creation alleviates poverty. e.g. tour guides, security personnel, and creating opportunities to sell and exhibit art work.
• Ownership of the concept leads to proper caring and protection of the fauna and flora. e.g. prevention of poaching, illegal smuggling of exotic animals and plants, discourages over exploitation of natural resources.
• Part of the income generated can be utilised for conservation and rehabilitation projects.
• Cementing strong partnership with the private and public sector could provide more management and financial support

Possible threats to ecotourism

• Poaching / illegal hunting
• Crime and violence against tourists
• Illegal trade of exotic plants and animals
• Illegal occupation of land and the establishment of squatter camps
• Natural disasters. e.g. wild fires, droughts, floods, etc.
• Deforestation• Extension of farming lands
• Illegal dumping of waste
• Illegal developments e.g. hotels and golf estates, airports, stadia. etc.
• Building of dams in an ecologically sensitive area
• Miningo Exploitation of tourists

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LIFE SCIENCES ESSAYS GRADE 10-12

The document provides a clear structure on how to write the essays. This document has been created from information available from the internet and it is not meant for any business purposes (FREE SUPPLY) but to help South African Life sciences Learners by gathering all the important information together. Not for market purposes only meant at assisting the Learners with a simple clear alternative in the essay writing, With a compilation of essays from Grade 12-10. You have to read the essays with understanding and never try to memorize them, as that is never part of learning. We aimed at creating independent and innovative thinkers of the south African as non-profit organization. Sources 1. I’solezwe lesiXhosa, 17 September, 2015 page 11 2. Life Sciences Academics (Facebook page), DR Marian Ross 3. http://www.testtakingpa.com/study/ 4. South African Department Basic Education Exam question papers and memorandums available from WWW.dbe.gov.za 5. Mr. Chaple's Science Class Blog http://chaplescienceclass.blogspot.com/2017/09/dnastructure.html 6. Eastern Cape Department of Education https://www.ecexams.co.za/ExaminationPapers.htm

Related Papers

Life Sciences have always been a fundamental area of science. The exponential increase in the quantity of scientific information and the rate, at which new discoveries are made, require very elaborate, interdisciplinary and up-to-date information and their understanding. This fourth edition of Life sciences, Fundamentals and practice includes extensive revisions of the previous edition. We have attempted to provide an extraordinarily large amount of information from the enormous and ever-growing field in an easily retrievable form. It is written in clear and concise language to enhance self-motivation and strategic learning skill of the students and empowering them with a mechanism to measure and analyze their abilities and the confidence of winning. We have given equal importance to text and illustrations. The fourth edition has a number of new figures to enhance understanding. At the same time, we avoid excess detail, which can obscure the main point of the figure. We have retained the design elements that have evolved through the previous editions to make the book easier to read. Sincere efforts have been made to support textual clarifications and explanations with the help of flow charts, figures and tables to make learning easy and convincing. The chapters have been supplemented with self-tests and questions so as to check one’s own level of understanding. Although the chapters of this book can be read independently of one another, they are arranged in a logical sequence. Each page is carefully laid out to place related text, figures and tables near one another, minimizing the need for page turning while reading a topic. I have given equal importance to text and illustrations as well. We hope you will find this book interesting, relevant and challenging.

Life Sciences have always been a fundamental area of science. The exponential increase in the quantity of scientific information and the rate, at which new discoveries are made, require very elaborate, interdisciplinary and up-to-date information and their understanding. This fourth edition of Life sciences, Fundamentals and practice includes extensive revisions of the previous edition. We have attempted to provide an extraordinarily large amount of information from the enormous and ever-growing field in an easily retrievable form. It is written in clear and concise language to enhance self-motivation and strategic learning skill of the students and empowering them with a mechanism to measure and analyze their abilities and the confidence of winning. We have given equal importance to text and illustrations. The fourth edition has a number of new figures to enhance understanding. At the same time, we avoid excess details, which can obscure the main point of the figure. We have retained the design elements that have evolved through the previous editions to make the book easier to read. Sincere efforts have been made to support textual clarifications and explanations with the help of flow charts, figures and tables to make learning easy and convincing. The chapters have been supplemented with self-tests and questions so as to check one’s own level of understanding. We hope you will find this book interesting, relevant and challenging.

Halus Satriawan

Bekele Gebreamanule

Joyce Wawira

By the end of the course, the learner should be able to: 1. communicate biological information in a precise, clear and logical manner 2. develop an understanding of interrelationships between plants and animals and between humans and their environment 3. apply the knowledge gained to improve and maintain the health of the individual, family and the community 4. relate and apply relevant biological knowledge and understanding to social and economic situations in rural and urban settings 5. observe and identify features of familiar and unfamiliar organisms, record the observations and make deductions about the functions of parts of organisms 6. develop positive attitudes and interest towards biology and the relevant practical skills 7. demonstrate resourcefulness, relevant technical skills and scientific thinking necessary for economic development 8. design and carry out experiments and projects that will enable them understand biological concepts 9. create awareness of the value of cooperation in solving problems 10. acquire a firm foundation of relevant knowledge, skills and attitudes for further education and for training in related scientific field.

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Grade 10 study guides: Life Sciences

We have compiled some study guides, practice papers and textbooks you can download for free to help your Grade 10 to prepare for the exams. Many private publishers also have great resources for Grade 10s, at a price, but it could be worth investing in. See below for links to the free ones. 

Via Afrika 

Educational book publisher Via Afrika has given us these Life Sciences study guides to distribute for free.

Grade 10 Life Sciences (English)

Grade 10 life sciences (afrikaans).

Here are the Siyavula study guides for Grade 10 learners writing Life Sciences.

Grade 10 Life Science Teacher's guide (English)

Grade 10 life science teacher's guide (afrikaans), more exam help:.

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Life Sciences

Most of the exam papers are available in English and Afrikaans

No June Exams was written due to covid

Exam papers and memos are essential resources for South African students preparing for their exams, and they can be found on various educational websites. Testpapers.co.za is a leading platform providing a comprehensive collection of past exam papers and memos for grades 1 to 12, covering subjects aligned with the CAPS curriculum in both English and Afrikaans. This site offers students an invaluable opportunity to practice with real exam questions and understand the marking schemes, enhancing their exam readiness. Testpapers.co.za features papers and memos from 2012 to 2024, ensuring students have access to the most recent and relevant materials. Additionally, the site provides study guides and summaries, making it a one-stop resource for all exam preparation needs. By utilizing Testpapers.co.za, students can gain a better understanding of exam formats, identify key topics, and improve their problem-solving skills. Whether it's for revision or practice, these online resources are indispensable tools for academic success. For a holistic approach to exam preparation, students are encouraged to explore and utilize all available resources, ensuring they are well-prepared to excel in their exams.

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2.3 Cell structure and function

2.3 Cell structure and function (ESG4S)

Section 3: Cell Structure and Function

In this section the learners now expand their knowledge and learn the various cell structures and related functions. The roles of the organelles within the cells need to be introduced and relate structure and location of organelles to their function.

Cells differ in size, shape and structure and therefore carry out specialised functions. Link this to tissues. The differences between plant and animal cells can be linked to Grade 9.

Cell theory (ESG4T)

The cell theory developed in 1839 by microbiologists Schleiden and Schwann describes the properties of cells. It is an explanation of the relationship between cells and living things. The theory states that:

• all living things are made of cells and their products.
• new cells are created by old cells dividing into two.
• cells are the basic building blocks of life.

The cell theory applies to all living things, however big or small. The modern understanding of cell theory extends the concepts of the original cell theory to include the following:

• The activity of an organism depends on the total activity of independent cells.
• Energy flow occurs in cells through the breakdown of carbohydrates by respiration.
• Cells contain the information necessary for the creation of new cells. This information is known as 'hereditary information' and is contained within DNA.
• The contents of cells from similar species are basically the same.

DNA (the hereditary information of cells) is passed from 'parent' cells to 'daughter' cells during cell division. You will learn more about this in the following chapter: Cell division .

Cells are the smallest form of life; the functional and structural units of all living things. Your body contains several billion cells, organised into over 200 major types, with hundreds of cell-specific functions.

Some functions performed by cells are so vital to the existence of life that all cells perform them (e.g. cellular respiration). Others are highly specialised (e.g. photosynthesis).

Figure 2.9 shows a two-dimensional drawing of an animal cell. The diagram shows the structures visible within a cell at high magnification. The structures form the ultrastructure of the cell.

Figure 2.9: Diagram of the cell ultrastructure of an animal cell.

The cell wall is a rigid non-living layer that is found outside the cell membrane and surrounds the cell. Plants, bacteria and fungi all have cell walls. In plants, the wall is comprised of cellulose. It consists of three layers that help support the plant. These layers include the middle lamella, the primary cell wall and the secondary cell wall.

Middle lamella : Separates one cell from another. It is a thin membranous layer on the outside of the cell and is made of a sticky substance called pectin.

Primary cell wall : Is on the inside of the middle lamella and is mainly composed of cellulose.

Secondary cell wall : Lies alongside the cell membrane. It is is made up of a thick and tough layer of cellulose which is held together by a hard, waterproof substance called lignin. It is only found in cells which provide mechanical support in plants.

The human body cannot break down the cellulose in cell walls because we do not produce the enzyme cellulase.

Figure 2.10: Scanning electron microscope micrographs of diatoms showing the external appearances of the cell wall. Scale bar: A, B, D: 10 um, C 20 um

Functions of the cell wall

• The main function of the wall is to protect the inner parts of the plant cell, it gives plant cells a more uniform and regular shape and provides support for the plant body.
• The cell wall is completely permeable to water and mineral salts which allows distribution of nutrients throughout the plant.
• The openings in the cell wall are called plasmodesmata which contain strands of cytoplasm that connect adjacent cells. This allows cells to interact with one another, allowing molecules to travel between plant cells.

Cell membrane (ESG4W)

The cell membrane , also called the plasma membrane, physically separates the intracellular space (inside the cell) from the extracellular environment (outside the cell). All plant and animal cells have cell membranes. The cell membrane surrounds and protects the cytoplasm . Cytoplasm is part of the protoplasm and is the living component of the cell.

The cell membrane is composed of a double layer (bilayer) of special lipids (fats) called phospholipids . Phospholipids consist of a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophobic head of the phospholipid is polar (charged) and can therefore dissolve in water. The hydrophobic tail is non-polar (uncharged), and cannot dissolve in water.

The lipid bilayer forms spontaneously due to the properties of the phospholipid molecules. In an aqueous environment, the polar heads try to form hydrogen bonds with the water, while the non-polar tails try to escape from the water. The problem is solved by the formation of a bilayer because the hydrophilic heads can point outwards and from hydrogen bonds with water, and the hydrophobic tails point towards one another and are 'protected' from the water molecules ( Figure 2.11 .

Figure 2.11: The lipid bilayer showing the arrangement of phospholipids, containing hydrophilic, polar heads and hydrophobic, non-polar tails.

Recall the structure of lipid molecules from the previous chapter on the chemistry of life .

All the exchanges between the cell and its environment have to pass through the cell membrane. The cell membrane is selectively permeable to ions (e.g. hydrogen, sodium), small molecules (oxygen, carbon dioxide) and larger molecules (glucose and amino acids) and controls the movement of substances in and out of the cells. The cell membrane performs many important functions within the cell such as osmosis, diffusion, transport of nutrients into the cell, processes of ingestion and secretion. The cell membrane is strong enough to provide the cell with mechanical support and flexible enough to allow cells to grow and move.

Watch a video about the cell membrane.

Video: 2CPB

Structure of the cell membrane: the fluid mosaic model

S.J. Singer and G.L. Nicolson proposed the Fluid Mosaic Model of the cell membrane in 1972. This model describes the structure of the cell membrane as a fluid structure with various protein and carbohydrate components diffusing freely across the membrane. The structure and function of each component of the membrane is provided in the table below. Table 2.2 refers to the components of the cell membrane shown in the diagram in Figures Figure 2.11 and Figure 2.12 .

Figure 2.12: Fluid mosaic model of the cell membrane.

A further description of the fluid mosaic model can be viewed at:

Video: 2CPC

Movement across membranes (ESG4X)

Movement of substances across cell membranes is necessary as it allows cells to acquire oxygen and nutrients, excrete waste products and control the concentration of required substances in the cell (e.g oxygen, water, hormones, ions, etc). The key processes through which such movement occurs include diffusion, osmosis, facilitated diffusion and active transport.

Learn about the different ways that molecules can travel across cell membranes.

Video: 2CPD

1. Diffusion

Diffusion is the movement of substances from a region of high concentration to low concentration. It is therefore said to occur down a concentration gradient . The diagram below shows the movement of dissolved particles within a liquid until eventually becoming randomly distributed.

Diffusion is a passive process which means it does not require any energy input. It can occur across a living or non-living membrane and can occur in a liquid or gas medium. Due to the fact that diffusion occurs across a concentration gradient it can result in the movement of substances into or out of the cell. Examples of substances moved by diffusion include carbon dioxide, oxygen, water and other small molecules that are able to dissolve within the lipid bilayer.

Watch diffusion taking place by clicking on the following link.

Video: 2CPF

Observing diffusion

To observe diffusion.

• 1 x \(\text{500}\) \(\text{ml}\) beaker
• large funnel
• plastic straw
• potassium permanganate crystals
• Fill a beaker with water and allow it to stand for a few minutes so that water movement stops.
• Place a large funnel into the water so that it touches the bottom of the beaker. Drop a few small potassium permanganate crystals through the straw. Remove the funnel carefully and slowly.
• Observe the size of the area that is coloured by the potassium permanganate at the beginning of the experiment, after 5 minutes and then after 20 minutes.
• What do you observe happening in the beaker?
• What can you conclude based on your observations?
• Explain how using hot water would affect the results of this experiment (remember that when you explain you need to give a reason for your answer).

Observing Diffusion

• The purple colour slowly spreads (diffuses) throughout the entire beaker of water, until the colour is evenly spread out.
• The molecules of water and potassium permanganate must be constantly moving in order for the purple colour to diffuse throughout the water and spread out evenly.
• Using hot water would speed up the spreading process/ diffusion. The additional heat from the water gives the particles kinetic energy which enables them to move more quickly. The faster the particles move, the faster the colour spreads/ diffuses throughout the beaker.

When the concentration of solutes in solution is low, the water concentration is high, and we say there is a high water potential . Osmosis is the movement of water from a region of higher water potential to a region of lower water potential across a semi-permeable membrane that separates the two regions. Movement of water always occurs down a concentration gradient, i.e from higher water potential (dilute solution) to lower potential (concentrated solution). Osmosis is a passive process and does not require any input of energy. Cell membranes allow molecules of water to pass through, but they do not allow molecules of most dissolved substances, e.g. salt and sugar, to pass through. As water enters the cell via osmosis, it creates a pressure known as osmotic pressure.

Watch osmosis taking place by clicking on the following link.

Video: 2CPG

In biological systems, osmosis is vital to plant and animal cell survival. Figure 2.15 demonstrates how osmosis affects red blood cells when they are placed in three different solutions with different concentrations.

Plant cells use osmosis to absorb water from the soil and transport it to the leaves. Osmosis in the kidneys keeps the water and salt levels in the body and blood at the correct levels.

Predicting the direction of osmosis

To predict the direction of osmosis.

• 1 x large potato
• potato peeler/scalpel
• concentrated sucrose/sugar solution. To obtain this, add 100 g of sugar to 200 ml of water.
• Peel off the skin of a large sized potato with a scalpel/potato peeler.
• Cut its one end to make the base flat.
• Make a hollow cavity in the potato almost to the bottom of the potato.
• Add the concentrated sugar solution into the cavity of the potato, filling it about half way. Mark the level by inserting a pin at the level of the sugar solution (insert the pin at an angle into the cavity at the level) ( Figure 2.16 A).
• Carefully place the potato in the beaker containing water.
• Observe what happens to the level of the sugar solution in the potato.
• After 15 to 20 minutes, mark the level by inserting the second pin at the level of the sugar solution (insert as the first pin) ( Figure 2.16 B).

• What do you observe happening to the level of the solution inside the potato?
• What conclusion can you draw based on your observation?
• What conditions were met in this experiment that makes this type of transport different to diffusion?
• The level of the solution inside the potato increases.
• Water moves out of the potato into the cavity in the middle. At the same time, water is drawn into the potato from the beaker. This means that the solution in the cavity is hypertonic and the water is hypotonic.
• The semi-permeable membranes of the cells in the potato prevented the sugar molecules from moving. Only the water moves. In diffusion, all molecules are able to move. In osmosis, only water moves, and it moves across a semi-permeable membrane.

Watch an illustration of diffusion and osmosis.

Video: 2CPH

3. Facilitated diffusion

Facilitated diffusion is a special form of diffusion which allows rapid exchange of specific substances. Particles are taken up by carrier proteins which change their shape as a result. The change in shape causes the particles to be released on the other side of the membrane. Facilitated diffusion can only occur across living, biological membranes which contain the carrier proteins. A substance is transported via a carrier protein from a region of high concentration to a region of low concentration until it is randomly distributed. Therefore movement is down a concentration gradient .

Examples of substances moved via facilitated diffusion include all polar molecules such as glucose or amino acids.

4. Active transport

Active transport is the movement of substances against a concentration gradient, from a region of low concentration to high concentration using an input of energy. In biological systems, the form in which this energy occurs is adenosine triphosphate (ATP) . The process transports substances through a membrane protein. The movement of substances is selective via the carrier proteins and can occur into or out of the cell.

ATP and ADP are molecules involved with moving energy within cells. You do not need to know these names in full and will learn more about them later.

Examples of substances moved include sodium and potassium ions as shown in Figure 2.18

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