Summary

Grade 10 Life Science November Exam Summary

0 purchase

Course
Life Sciences

Institution
10th Grade

This document contains the following topics: -Respiration: Release of Energy -Nutrition in the Human Body -Gaseous exchange -Gaseous Exchange System in the Human Body -Biosphere to Ecosystems -Biodiversity -History of Life on Earth -Magnification calculations

[Show more]

Preview 4 out of 36 pages

View example

Uploaded on January 29, 2025
Number of pages 36
Written in 2024/2025
Type Summary

summary

Institution 10th Grade
Course Life Sciences
Schooljaar 200

Respiration: Release of Energy
Life Science

Respira on
 Each cell in org needs energy perform normal life func ons.
 Energy obtained through metabolic breakdown process where organic compounds mainly carbohydrates broken down
gradually to release energy in small quan es. This series reac ons known cellular respira on, occur all living cells.
 Oxygen needed usually together with organic molecule, apart from energy also produces water, CO2 as waste products.
 Water go en rid of:
- Urine.
- Sweat.
- Breathing out water vapour.
 Plant cells also respire to provide their energy needs.
 Cellular Respira on compared to combus on:
- Both processes need fuel.
- Both need Oxygen.
- Both release CO2 and water.
- Both processes release energy.
 ATP( adenosine triphosphate). Means 3 phosphate bonded to adenosine.

Cellular Respira on
 Most eukaryo c, prokaryo c orgs respire aerobically, process needs oxygen.
 Orgs can also respire in absence oxygen called anaerobic respira on(oxygen independent respira on).
 Most cells use aerobic respira on to obtain energy, more eﬃcient than anaerobic respira on.
 C6H12O6 + 6O2  6CO2 + 6H2O + energy(form of ATP)
 Aerobic respira on occurs mainly in mitochondria cells. Four stages are iden ﬁed in this process.

Aerobic respira on
1. Glycolysis in the Cytoplasm:
 Glucose(6C compound) broken down into 2 molecules of pyruvic acid(3C compound).
 During this phase 2 ATPs are produced.
 Hydrogens (energy rich) removed, bind temporarily with hydrogen carrier NAD. NADH used last stage.
 Glycolysis does not need oxygen. This stage is anaerobic.
2. Forming of Acetyl Co-enzyme A(2 C compound):
 A CO2 is removed and released.
 The 2 C-compound is carried into mitochondrion by co-enzyme A as Acetyl co-enzyme A.
 Although oxygen not involved in this process, will not start without suﬃcient oxygen available for rest of process(type of
control mechanism.
 1 Glucose= 2x Krebs Cycle.
3. Krebs cycle(also citric acid cycle):
 Process occurs in mitochondrion.
 CO2 released.
 Energy-rich hydrogen is released.
 These hydrogens temporarily bind with hydrogen carriers NAD and FAD.
 2 ATPs are produced.
 Glucose is now broken down.


,4. Hydrogen Transfer System(electron transfer system or oxida ve phosphoryla on):
 Process occurs in mitochondrion.
 Energy of hydrogens is removed step-by-step to form ATP.
 Exhausted hydrogens bind with oxygen to form water.
 Each hydrogen has enough energy form 3 ATPs. So one glucose molecule can provide 36(12x3)+2(glycolysis)=38 ATPs.

Anaerobic Respira on
 Respira on in absence oxygen, can occur in plant and animal cells.
 Many unicellular orgs, o en pathogens, have ability to respire anaerobically.
 Animal cells: lac c acid fermenta on. Plant cells: Alcoholic fermenta on.
 Anaerobic respira on also uses glucose as fuel, delivers less energy per reac on.

Lac c Acid Fermenta on:
 C6H12O6 Pyruvic acid Lac c acid + 2ATP
 When muscle cells experience oxygen deﬁciency e.g., run long me, large amounts of pyruvic acid builds up in cells.
 Krebs cycle can’t start, as not enough oxygen available. Pyruvic acid now converted to lac c acid.
 This remains cells. It is lac c acid responsible for s ﬀ, sore feeling when want to move next day.
 Bets way to get rid of s ﬀ, sore feeling do light exercise. Blood ﬂow to muscle increases, more oxygen taken to cells lac c
acid can be converted into pyruvic acid so respira on can con nue normally.
 Even during normal exercise lac c acid produced when oxygen provision to muscle cells not quite suﬃcient. About 80% of
this lac c acid taken liver, used form glucose can serve as source energy. Other 20% returned normal respira on process.
 Humans can only rely ATP released by lac c acid fermenta on for few minutes, Many animals not need that much energy.
 Red-ear turtle can remain under water 2 weeks without breathing air. Respire aerobically under normal condi ons, but
under water are rela vely inac ve, do not need much energy.
 Bacteria causes milk go sour, are orgs that use this type respira on sa sfy their energy needs.

Alcoholic Fermenta on:
 Yeast cells(type fungus) respire anaerobically to produce alcohol, CO2, ATP. Type alcohol produced ethanol(ethyl alcohol).
 This process especially important in beer, wine, spirits industry.
 C6H12O6 CO2 + ethanol + 2 ATP
 Yeast cells also used bake bread.
 Sweet smell of baking bread is because of ethanol(all of it evaporates in heat), texture bread( ny cavi es) caused by carbon
dioxide bubbles. Large hole in bread occurs when dough and yeast not mixed properly.
 Both Lac c acid fermenta on, alcoholic fermenta on not energy eﬀec ve processes at all.
 Combus on glucose not complete only 2 molecules of ATP produced during each of these reac ons.
 In contrast aerobic respira on delivers 36 to 38 ATPs per glucose molecule.
 Fact fermenta on is so ineﬀec ve means large quan es glucose needed.
 To preform same amount of work anaerobic cells need 20 mes as much fuel per second as aerobic cell.
 This why muscle cells store so much glucose as glycogen-cells can respire anaerobically for short periods.

A (cellular fuel) Glucose
B (end product) Lac c acid
C (end products) CO2, ethanol
D (end product) CO2, H2O
E (molecule formed) ATP
1 Lac c acid fermenta on
2 Alcoholic fermenta on
3 Cellular respira on

,Prac cal Inves ga ons

Heat Energy Released During Respira on
 Use enough seeds ensure both ﬂasks will be at least ¾ full.
 Soak seeds approximately 24 hours water allow them to stand for 48 hours to
germinate.
 Place half seeds in boiling water to kill them.
 Soak both dead, living seeds in formaldehyde-solu on for about 5 min
(Solu on: 1 part formaldehyde with 10 parts water).
 Rinse seeds thoroughly with boiled cooled down water.
 Set up apparatus as in picture.
 Thermos ﬂasks placed upside down to trap heat as heat rises.

Flask with live seeds Flask with dead seeds
Temp at start experiment 24 °C 24 °C
Temperature a er 48 hours 32 °C 24 °C

Carbon Dioxide Released During Respira on
 Set up apparatus as in picture.
 Soak seeds for about 24 hours in water.
 Ensure lime water is clear.
 Remember clean test tubes, may not be any other chemical substances present that
might react with lime water.
 Place apparatus in warm place 24 hours.
 Test tube A clear lime water will turn milky(as CO2 present).
 Test Tube B clear lime water will stay clear (no CO2 present).

, Nutrition in the Human Body
Life Science

Nutri on in the Human Body
 3 Biological reasons why nutri on necessary:
- Provision energy for day-to-day ac vi es, on cellular level.
- Availability material growth, healing wounds, replacement damaged/worn
ssues.
- Regula on processes in body.
 Processes involved in nutri on:
1. Inges on: Intake food.
2. Diges on: Breakdown insoluble polymers(macromolecules)-smaller, soluble
monomers(building blocks).
3. Absorp on: Absorp on nutrients. Absorbed nutrients used variety
process body. Known as assimila on nutrients.
4. Eges on: Undigested food residues expelled. Solid waste=faeces,
process defaeca on.
5. Excre on: Waste products produced during metabolic reac ons
expelled. In liquid form.
 Human body’s diges ve system highly specialised involve all steps nutri on.
 Diges ve system consists diges ve tract, associated organs(glands).

Mouth Teeth. Tongue and Salivary Glands
 Adult human 32 teeth.
 Human=heterodont, teeth have diﬀ structures, func ons. Teeth dolphin all look same, dolphin is homodont.
 Human=diﬁodont, have 2 sets teeth, set milk teeth, permanent set. Animals not lose baby teeth= monoﬁodont.

Teeth

Types of Teeth and their Func ons:
 Incisors (i): 4 in upper, lower jaw cut, bite oﬀ food. Sharp, chisel-shaped. 1 Root.
 Eye teeth/canines(c): 2 top, bo om used bite oﬀ/tear food/hold on to it. NB
predators, use canines kill prey. 1 Root.
 Premolars(pm): 4 top, bo om. Grind food. 2 roots.
 Molars(m): 6 top, bo om. Grind food. 2 roots.

General Structure of a Tooth:
 Tooth consist den ne(substance similar bone, with higher mineral content. Ensures
den ne harder bone.
 Part protrudes above gum(crown of tooth) covered tooth enamel(hardest substance
body).
 Dental cavity ﬁlled so type connec ve ssue containing blood, lymph vessel, nerves.
 Tooth embedded with cement in socket(cavity in jaw).
 Part embedded socket called root.
 Nerves, blood vessels, lymph vessels enter tooth from jaw through root canal.

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying this summary from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller jennsmith. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy this summary for R194,99. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

64232 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy summaries for 15 years now

Start selling

Seller

Summary ·