Chapter Summary
Class 10 Science
Chapter 6 - Life Processes
1.
Aerobic
Respiration (Mitochondria)
Class 10 Science
Chapter 6 - Life Processes
Life
processes are functions that help maintaining life. They are required for
sustaining life. They are also called maintenance processes.
Nutrition –
Obtaining food from environment & its conversion into simpler forms
Respiration –
Breaking down simpler molecules to obtain energy (ATP)
Transportation – Transport
of substances, water, minerals, etc.
Excretion – Removal of harmful
waste from the body.
Modes of Nutrition among organisms
|
|
Autotrophic
Organisms
prepare their own food using raw materials
Eg:
Green Plants
|
Heterotrophic
Organisms
depend on other organisms for food
Eg:
Humans, Worms
|
Autotrophic
Nutrition
Green
plants, perform photosynthesis, the process by which they use raw materials and
prepare Glucose (product) & and store in the form of Starch.
Steps involved in
Photosynthesis:
1. Absorption
of sunlight by chlorophyll and conversion into chemical energy
2. Splitting
of water using chemical energy and removal of O2 as waste product.
3. Reduction
of CO2 by adding protons, to obtain glucose as the final product
Desert plants
(Xerophytes) do photosynthesis in two steps. They prepare an
intermediate during the night by using CO2 and minimum water. In the
morning the intermediate in converted to glucose by the help of Sunlight. This
preserves water.
Stomata
Stomata are tiny openings on leaf surface. Stomata
opening is controlled by guard cells which Change shape by absorbing &
losing water from surrounding cells.
Mechanism of Stomata Opening and Closing.
Guard cells absrob ions, creating a high osmotic pressure outside, causing water to enter the guard cells. Endosmosis causes guard cells to swell, stomata opens.
Guard cells loose ions actively, creating high osmotic pressure inside, causing water to move out of the guard cells. Exosmosis causis guard cells to shrink, stomata closes.
Is sunlight
required for photosynthesis?
A
small activity can be performed to ascertain whether sunlight is required for
photosynthesis.
The covered leaf, not exposed to sunlight, will not give a blue black color with iodine solution. This shows that in the absence of sunlight, photosynthesis did not occur and starch was not formed.
Heterotrophic Nutrition.
Heterotrophic Nutrition Types
|
|
Holozoic
|
Organism
engulfs food and breaks it down using enzymes (Humans)
|
Parasitic
|
Parasite
derive nutrition fro Host without benefitting
|
Saprophytic
|
Saprophyte
derives nutrition from dead matter
|
Symbiotic
|
Organisms
depend on each other
|
Human Digestion
Human
digestion occur in the alimentary canal(Mouth to anus). The entire passage is called Human Digestive System.
Steps
·
Food is chewed by teeth, mixed with saliva
from salivary glands. Salivary amylase convert
starch to sugar
·
HCL in the
stomach creates acidic medium to allow pepsin
to act on proteins. Mucus protects
stomach wall.
·
Small intestine – longest part of
alimentary canal has 3 sections – Deodenum,
Ileum, Jejunum.
·
Common
Bile Duct
brings intestinal enzymes from Liver & Pancreas
·
Bile creates
basic medium for Trypsin to act on
remaining proteins
·
Bile
Salts
emulsifies fat for Lipase to act on them
·
Pancreatic
Amylase
acts on remaining Carbohydrates.
Summary of the process of digestion.
Complex Nutrients
|
Enzymes involved
|
Digested Subunits
|
Carbohydrate
|
Salivary
Amylase, Pancreatic Amylase
|
Glucose
|
Proteins
|
Pepsin(HCL),
Trypsin(Bile)
|
Amino
Acids
|
Fats
|
Lipase
|
Fatty
Acid
|
·
Finally digested subunits are absorbed into
the finger like projections on the wall of intestine (villi) which are supplied
with blood vessels.
·
Large intestine absorbs water &
minerals.
·
Waste (faecal matter) is removed through anus.
Tooth Decay
Bacteria
act on the left over food on the teeth and produces acid. This slowly eats up
the
dentine and causes Tooth Decay, can be prevented by brushing with
Toothpaste.
Respiration
Involves
breakdown of absorbed subunits into ATP using O2 gas, which is
obtained by the process of breathing (Lungs)
- Glucose is converted to pyruvate in the cytoplasm
- Pyruvate gets oxidised in 3 ways to attain ATP
Complete
oxidation of pyruvate in adequate supply of O2. Maximum ATP produced
2.
Anaerobic
Respiration (Muscle Cells)
Incomplete
oxidation of pyruvate due to lack of O2. Lactic acid produced,
accumulation cause muscle cramps.
3.
Fermentation
(Yeast Cells)
Incomplete
oxidation of pyruvate. Alcohol produced, used for making wine & beer.
CO2
is produced as a cellular waste, which is removed from tissues by getting
dissolved into blood.
The
lungs are designed to maximise exchange of O2 & CO2.
The
alveoli are spherical in shape, have blood vessels and are moist, to maximise
exchange of gases.
The design of lungs is such, that the surface area for diffusion of gases is huge. This makes the breathing process highly efficient.
The haemoglobin
helps in transferring O2 to
the tissues efficiently by binding to it.
