Life Sciences Essays for Grade 12 11 and 10

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

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

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


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 √


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

  1. Brief explanation of what ecotourism entails,
  2. 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
  • Pollution
  • 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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Differences between DNA and RNA: South African Curriculum CAPS (South Africa)

Differences between DNA and RNA: South African Curriculum CAPS (South Africa)

Differences between DNA and RNA: South African Curriculum CAPS (Grade 12, Grade 11, Grade 10) (South Africa): DNA stands for deoxyribonucleic acid, while RNA is ribonucleic acid. Although DNA and RNA both carry genetic information, there are quite a few differences between them. This is a comparison of the differences between DNA versus RNA, including a quick summary and a detailed table of the differences.

Summary of Differences Between DNA and RNA

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  1. DNA contains the sugar deoxyribose, while RNA contains the sugar ribose. The only difference between ribose and deoxyribose is that ribose has one more -OH group than deoxyribose, which has -H attached to the second (2′) carbon in the ring.
  2. DNA is a double-stranded molecule, while RNA is a single-stranded molecule.
  3. DNA is stable under alkaline conditions, while RNA is not stable.
  4. DNA and RNA perform different functions in humans. DNA is responsible for storing and transferring genetic information, while RNA directly codes for amino acids and acts as a messenger between DNA and ribosomes to make proteins.
  5. DNA and RNA base pairing is slightly different since DNA uses the bases adenine, thymine, cytosine, and guanine; RNA uses adenine, uracil, cytosine, and guanine. Uracil differs from thymine in that it lacks a methyl group on its ring.
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Why is DNA replication important

Why is DNA replication important? CAPS (South Africa)

Why is dna replication important to the growth and development of a multi-cellular organism and all living organisms: South African Curriculum: CAPS. Grade 12, Grade 11, and Grade 10.

DNA replication is important because it:

Doubles the genetic material so it

  • can be shared between the resulting daughter cells during cell division.
  • Results in the formation of identical daughter cells during mitosis.

Why is dna replication important to the growth and development of a multi-cellular organism and all living organisms

DNA replication must occur for cells to divide and specialize, and for a multi-cellular organism to grow. Each time cells divide, the entire set of chromosomes has to be replicated. What actually happens at the molecular level is the “unzipping” of the DNA strands just before division, with each chromosome being duplicated before the duplicates move to each of the two cells being formed (regular cell division — mitosis). During the process, the entire strands of DNA are replicated. Each “daughter” cell receives the complete set of DNA that has just been replicated, not just a portion of the total.

What’s really interesting is specialization of cells in multi-celled organisms, like humans. We have 3 main kinds of muscle cells, 3 main kinds of nerve cells, plus bone, skin, and blood cells, and that’s really just scratching the surface in describing specialization. Each of these types of cells retains the entire DNA sequence, but various segments of the genes are “turned on” for different purposes. Red blood cells lose their nuclei and don’t reproduce in the bloodstream. Every time cells divide in a human embryo there is slightly more specialization, due to the effect of the genes presenting their specialized effects at the appropriate time. When you consider the complexity of the process, it’s amazing that anyone is born “normal.”

The sex cells that will be transmitted to the offspring are a special case of replication, because “reduction division,” or meiosis, results in the sex cells having half the normal number of chromosomes, which normally occur in pairs. This allows half the chromosomes from the mother to combine with half from the father to form a new organism with a complete set of chromosomes. All organisms that reproduce sexually undergo meiosis to form sex cells. The “parent” cells first divide to produce two daughter cells that have the full set of chromosomes, and then these daughter cells divide without replicating the chromosomes, so they have half the normal number. One of each pair of chromosomes goes to the resulting sex cells. That’s why men produce both ‘X’ sperm and ‘Y’ sperm, because those sex chromosomes are normally paired together

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