1. Ecology

2. What is Ecology?
Ecology is the study of interactions among organisms and between organisms and their environment.
Biosphere contains the combined portions of the planet in which life exists, including land, water, and air or atmosphere.

3. Levels of Organization
Species is a group of organisms so similar to one another that they can breed and produce fertile offspring.
Population are groups of individuals that belong to the same species and live in the same area.
Communities are assemblages of the different populations that live together in a defined area.
Ecosystem is a collection of all the organisms that live together in a particular place as well as their nonliving or physical environment.
Biome is a group of ecosystems that have the same climate and similar dominant communities.

4. Animals get their food …5
by eating
plants or ...
or (c) other animals
... plant
products,
Plants make their food by photosynthesis

5. Energy Flow
Sunlight is the main source of energy for life on Earth.
Organisms are divided into two groups based on how they obtain their Energy
1. Autotrophs : Make their own food by converting energy and chemicals into food
2. Heterotrophs: Must eat other organisms for their food.

6. Energy Flow Autotrophs
The best know autotrophs are those that harness the power of the sun through photosynthesis. They use this energy to convert carbon dioxide and water into oxygen and glucose.
The second type of autotrophs use chemical energy to make carbohydrates. This is performed by several types of bacteria.

7. Energy Flow Types of Heterotrophs
Herbivores obtain energy by eating plants.
Carnivores eat animals.
Omnivores eat both plants and animals.
Detritivores feed on the remains of plants, animals and other dead matter.
Decomposers breaks down organic matter.

8. Feeding Relationships
Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).
Food Chains are a series of steps in which organisms transfer energy by eating or being eaten.
Food webs show the complex interactions within an ecosystem.
Each step in a food chain or web is called a trophic level. Producers make up the first step, consumers make up the higher levels.

9. Food Chain
A Food Chain is a series of steps in a community of organisms that is used to transfer ENERGY and MATTER by eating or being eaten.`
The Steps are Called
TROPHIC LEVELS

10. Food Web A Food Web is a series of interconnected food chains
Can You Still Identify the Trophic Levels here?

11. Food Web

12. Ecological Pyramids
An ecological pyramid is a diagram that shows the relarive amounts of energy or matter contained within each trophic level in a food web or food chain.
Energy Pyramid only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level.

13. Roughly 10% of the energy is transferred

14. Pyramids Continued
Biomass pyramids show the total amount of living “food” available at each trophic level.
Numbers pyramid shows the number of species at each trophic level.
Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one 10th the amount of living tissue.

15. BIOMASSPyramid

16. How do plants get their food ?2
How do plants get their food ?
73.943kg
soil
74kg soil
In the 17th Century, A Belgian physician, van Helmont, set up an
experiment in which he planted a willow sapling in a weighed
amount of soil.
The soil was watered but nothing else was added. After 5 years, the
tree had gained 74kg in weight but the soil had lost only 57g.
van Helmont concluded that the tree had made 74kg of new growth
from water alone

17. 3
van Helmont’s experiment was effective in showing that the plant’s food did not come from the soil.
But he had overlooked the fact that air was available to the plant as well as water.
Could it be that the plant made 174kg of material from just air and water?
This might seem unlikely but we now know that plants do indeed make their food from carbon dioxide from the air and water from the soil.

18. carbon sunlight dioxide (energy) water 9
The carbon dioxide comes from the air.
The water comes from the soil.
The energy comes from sunlight.
water

19. Photosynthesis Green plants take in carbon dioxide (CO2) from the air6
Photosynthesis
Green plants take in carbon dioxide (CO2)
from the air
They take up water (H2O) from the soil
The plants combine the CO2 with the H2O to
make the sugar, glucose (C6H12O6)
When a plant is photosynthesising, it is taking in carbon dioxide and giving out oxygen.
Plants which live in ponds, streams etc. are immersed in the water they need for photosynthesis
6CO H2O = C6H12O O2
Oxygen (O2) is a by-product of this reaction

20. Photosynthesis

21. Photosynthesis

22. Energy It takes energy to make CO2 combine with H2O9
Energy
It takes energy to make CO2 combine with H2O
This energy comes from sunlight
The energy is absorbed and used by a substance called chlorophyll
Without sunlight, photosynthesis could not take place.
Without photosynthesis, plants could not survive.
Without plants, most animals would die out because, ultimately, animals depend on plants for their food.
e.g. sunlight >>>> plants >>>> herbivores >>>> carnivores

23. Leaf Anatomy

24. Chlorophyll Chlorophyll is a green coloured chemical10
Chlorophyll
Chlorophyll is a green coloured chemical
It is present in the leaves of green plants
The chlorophyll in the cells is packaged into tiny structures called chloroplasts
The next slide shows a diagram of leaf cells with their chloroplasts
It is not only the leaves that contain chlorophyll; any green part of a plant, leaves, leaf stalk, stem, sepals will contain chloroplasts.

25. Plant Cell

27. Anatomy of a Leaf

29. What happens to the glucose?15
What happens to the glucose?
The glucose made by the chloroplast is either
(a) used to provide energy for the chemical processes in the cell ( by respiration)
(b)turned into sucrose and transported to other parts of the plant or
(c) turned into starch and stored in the cell as starch grains
In darkness the starch is changed back into glucose and transported out of the cell
Before it is transported, glucose is converted to sucrose. Two glucose molecules combine to make a molecule of sucrose.
2C6H12O6 = C12H22O H20
glucose sucrose
It is the sucrose which is transported throughout the plant

30. The energy needed for this process comes from sunlight 23
TO SUM UP
Plants combine carbon dioxide from the air, and water from the soil to make glucose.
The energy needed for this process comes from sunlight
The sunlight is absorbed by chlorophyll contained in the chloroplasts of the leaf.
The glucose can be used for energy or to make other substances.
To make other substances, the glucose must be combined with other chemical elements such as nitrogen and potassium.
These chemical elements are present in the soil and are taken up in solution by the roots.

31. Respiration = use of oxygen to burn food for energy

32. Respiration Chemical Formula
It’s the Reverse of Photosynthesis

33. Feeding Animals get their food by eating plants, or other animals4
Animals get their food by eating plants, or other animals
Carnivores eat animals
Herbivores eat plants
Plants make their own food
They combine carbon dioxide from the air with water and dissolved salts from the soil
Plants do NOT get their food from the soil
The process by which plants make food is called PHOTOSYNTHESIS
Most fungi and bacteria get their food by breaking down organic matter, such as plant and animal remains (detritus). They then absorb the soluble breakdown products.
These organisms are called detritivores.
The name ‘Photosynthesis’ is derived from ‘photo’ (light) and ‘synthesis’ (building up).
Plants synthesize their food with the aid of sunlight. (Slides 9 and 10).

34. Question 1 For a plant to make glucose it needs (a) CO2 and H2O25
For a plant to make glucose it needs
(a) CO2 and H2O
(b) CO2, H2O and sunlight
(c) CO2, H2O, sunlight and chlorophyll
(d) CO2, H2O, sunlight, chlorophyll
and nitrates

35. Question 2 A by-product of photosynthesis is (a) Water vapour26
Question 2
A by-product of photosynthesis is
(a) Water vapour
(b) Oxygen
(c) Carbon dioxide
(d) Nitrogen

36. Question 3 29
The food made by photosynthesis is stored as the plant in the form of
(a) Glucose
(b) Sucrose
(c) Starch
(e) Cytoplasm

37. Cycles of Matter
Unlike the one-way flow of energy, matter is recycled within and between ecosystems.
These cycles are the water cycle, Nutrient Cycle, Carbon Cycle, nitrogen cycle and phosphorus cycle.
These cycles are important so that the matter can be re-used by living things.

38. Carbon Cycle

39. Oxygen/Carbon Cycle

40. Nitrogen Cycle

41. The Nitrogen Cycle Nitrogen gas (N2)
Plants Make Proteins with Nitrates
Animals Make Proteins by consuming Plant or other organisms
Waste
Soil Bacteria
Soil Bacteria
Nitrite (NO2)
Nitrate NO3
Nitrate (NO3)

42. Nitrogen Cycle WASTE (NH3) (NH4+) (NO2) Nitrite _NITROSOMONAS into
FOOD contains PROTEIN
Nitrogen is in the fish in the form of
PROTEIN__
NO3 is absorbed by the plant roots and made into
__________________________ that can be used in food
Nitrogen in the waste is in the form of
AMMONIA NH3
WASTE (NH3)
(NH4+)
Uneaten food is decomposed into Ammonia (NH3) by
BACTERIA
NO3 is eaten “decomposed by a bac3erial called
__NITROBACTER__ into
____NITRATE, NO3 ___
Ammonia is eaten “decomposed” by a bacteria called
_NITROSOMONAS into
NITRITE, NO2
(NO2)
Nitrite

43. Nitrates Nitrates are present in the soil, dissolved in water19
Nitrates
Nitrates are present in the soil, dissolved in water
The plants take up nitrates in the soil water
The nitrates are conducted through the roots to the stem and then to the leaves
In the leaves, the nitrates and glucose are combined to make proteins
This process is called assimilation
Proteins are needed for making the cell structures, e.g. cytoplasm, nucleus, chloroplasts.
The plant can grow only by making new cells and cell structures
Strictly speaking, it is not nitrates salts that are taken up but nitrate ions. When a salt such as potassium nitrate, is dissolved in water it splits into positively charged potassium ions and negatively charged nitrate ions.
KNO3 becomes K+ and NO3- The plant may take up either or both of these ions.