Chapter Summary - Class 10 - Ch 6 Life Processes

Chapter Summary
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

1.    Aerobic Respiration (Mitochondria)

          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.