Online Notes on Chapter = 6 ( life processes) Part 3

This is Online Notes on Chapter = 6 ( life processes)  Part 3 for 
preparation of CBSE BOARD Examination, NTSE etc.



Blood:

Lymph : A yellowish fluid escapes from the blood capillaries into the intercellular spaces contain less proteins than blood. Lymph flows from the tissues to the heart assisting in transportation and destroying germs.

Blood Vessels:

Function :

(a) Absorption and upward movement of water and minerals by creating PULL.

(b) Helps in temperature regulation in plant.

Transport of food from leaves (food factory) to different part of the plant is called Translocation.

EXCRETORY SYSTEM IN MAN

Excretory/urinary system consists of :

(1) The kidneys : The excretory organ

(2) The ureters : The ducts which drain out urine from the kidneys

(3) The urinary bladder : The urinary reservoir

(4) The urethra : The channel to the exterior

                   The human excretory system

EXCRETION

1. The metabolic activities in the body generates many kinds of wastes including

nitrogenous wastes which are harmful for the body and hence needed to be removed.

Excretion is a process by which these wastes are removed from our body.

2. Unicellular organisms remove these wastes by simple diffusion.

Human Excretory System

Formation of Urine:

• Each kidney contains many filtration units called as nephrons.

• Nephrons are made up of a cluster of thin walled capillaries called glomerulus

which is associated with a cup like structure called as Bowman’s capsule and the

long tube which terminates through this capsule.

• The renal artery brings oxygenated blood to the kidneys along with the nitrogenous wastes like urea and uric acid and many other substances.

• The blood gets filtered through the glomerulus and this filtrate enters the tubular part of nephron.

• As this filtrate moves down the tubular part, glucose, amino acids, salts and excess of water gets selectively reabsorbed by the blood vessels surrounding these tubules.

• The amount of water reabsorbed depends upon :

* How much excess of water is there in the body and,

* How much nitrogenous wastes need to be excreted out.

• So the fluid now flowing in the tubular part is urine which gets collected in collecting ducts of nephrons.

• These collecting ducts together leave the kidney at a common point by forming the ureter.

• Each ureter drains the urine in the urinary bladder where it is stored until the

pressure of expanded bladder leads to an urge to pass it out through urethra.

• This bladder is a muscular structure which is under nervous control.

• 180 litres of filtrate is formed daily but only 2 litres is excreted out as urine so the rest is reabsorbed in the body.

Functions of Nephron:

• Excretion of nitrogenous wastes.

• To maintain the water and ionic balance (osmic regulation).

Excretion in Plants:

Plants use different strategies for excretion of different products :

• Oxygen and carbon dioxide is diffused through stomata.

• Excess water is removed by transpiration.

Plants can even loose some of their old parts like old leaves and bark of tree.

• Other waste products like raisins and gums especially in old xylem cells which canalso be lost by plants.

• Plants also secrete some waste substances into the soil around them

                                               Structure of a Nephron

The urine formation involves three steps :

1. Glomerular filtration : Nitrogenous wastes, glucose water, amino acid filter from the blood into Bowman Capsule of the nephron.

2. Tubular reabsorption : Now, useful substances from the filtrate are reabsorbed back by capillaries surrounding the nephron.

3. Secretion : Urea, extra water and salts are secreted into the tubule which open up into the collecting duct & then into the ureter.

Artificial Kidney:

Haemodialysis : The process of purifying blood by an artificial kidney. It is meant for kidney failure patients.

Online Notes on Chapter = 6 ( life processes) Part 2

This is Online Notes on Chapter = 6 ( life processes)  Part 2 for 
preparation of CBSE BOARD Examination, NTSE etc.



RESPIRATION:

Respiration involves :

(i) Gaseous exchange : 
Intake of oxygen from the atmosphere and release of CO2 → Breathing

(ii) Breakdown of simple food in order to release energy inside the cell → Cellular respiration


Breakdown of Glucose by Various Pathways:

Human Respiratory System:


Passage of air through the respiratory system :

Exchange of gases between alveolus, blood and tissues:

(i) Air (rich in O2) → Blood → Binds with haemoglobin in RBC → O2 is released in (in alveolus) (through blood vessels) tissues

(ii) CO2 → Released in blood → Dissolved in blood → Blood vessels → Released in alveolar sac → Sent out through nostrils (from tissue) (in alveoli)

Terrestial organisms : Use atmospheric oxygen for respiration

Aquatic organisms : Use dissolved oxygen for respiration

Respiration in plants:

Respiration in plants is simpler than the respiration in animals. Gaseous exchange occur through :

(a) Stomata in leaves

(b) Lenticels in stems

(c) General surface of the root Transportation

Human beings like other multicellular organism need regular supply of food, oxygen etc.

This function is performed by circulatory system.

Pulmonary Circulation : Blood moves from the heart to the lungs and back to the heart.

• Systemic Circulation : Blood moves from the heart to rest of the body and back to the heart.

Online Notes on Chapter = 6 ( life processes) Part 1

This is Online Notes on Chapter = 6 ( life processes)  Part 1 for 
preparation of CBSE BOARD Examination, NTSE etc.

All living things perform certain life processes like growth, excretion, respiration,
circulation etc.
All the processes like respiration, digestion, which together keep the living organisms
alive and perform the job of body maintenance are called life processes.

Raw Materials for Photosynthesis :
• Sunlight
• Chlorophyll → Sunlight absorbed by chlorophyll
• CO2 → Enters through stomata and oxygen (O2) is released as by-product through
stomata on leaf.
• Water → Water + dissolved minerals like nitrogen, phosphorus etc. are taken up by the
roots of the soil.
Site of Photosynthesis :
Chloroplast in the leaf, chloroplast contain chlorophyll (green pigment).
Main Events of Photosynthesis :
• Absorption of light energy by chlorophyll
• Conversion of light energy into chemical energy + splitting (breaking) of water into
hydrogen and oxygen
• Reduction of CO2 to carbohydrates
Stomata : Tiny pores present on the surface of the leaves.
Functions :
(a) Exchange of gases O2/CO2.
(b) Loses large amount of water (water vapour) during transpiration.

How do organisms obtain their food
Unicellular/Single celled organisms : Food is taken up through entire surface.
Example : (i) Amoeba
(ii) Paramaecium

Different organisms utilize different nutritional processes as it depends upon the source
of carbon from where the food is taken.

Online Practice Q_ANS on CHAPTER => 9 (Heredity and Evolution )

This is Online Practice Q_ANS on CHAPTER => 9 (Heredity and Evolution )for preparation of CBSE BOARD Examination, NTSE etc.


VERY SHORT ANSWER TYPE QUESTIONS (1 Mark):

1. Write the scientific name of men and garden pea.
2. Where are genes located ?
3. No two individuals are absolutely alike in a population. Why ?
4. What are the chromosomes XY and XX known as ?
5. Name five varieties of vegetables which have been produced from ‘wild
cabbage’ by the process of artificial selection.

SHORT ANSWER TYPE QUESTIONS (2 Marks):

1. Differentiate between homologous and analogous organs, with examples.

2. What are fossils ? How can the age of fossils be determined ?

SHORT ANSWER TYPE QUESTIONS (3 Marks):

1. Variation is beneficial to the species but not necessarily for the individual.
Give three reasons to justify it.

2. The human hand, cat paw and horse foot, when studied in detail show the
same structure of bones and point towards a common origin.
(a) What do you conclude from this ?
(b) What is the term given to such structures ?

LONG ANSWER TYPE QUESTIONS (5 Marks):

1. Which one is the edible part in kale, kohlrabi, broccoli, cabbage and
cauliflower ?
2. Name a recessive trait which is quiet common in human beings.

VALUE BASED QUESTION:

Raghu often taunts his wife for having only daughters and no son. As a
student of biology, how will you convince Raghu that his wife has no role in
giving birth to girls only ?

Hints to Long Answer Type Questions:

1. Kale - Large leaves
Kohl rabi - Swollen part
Broccoli - Arrested flower
Cauliflower - Sterile flower
Cabbage - Leaves with short distance between them

2. (a) Human height
(b) Skin colour
(c) Attachment of ear lobes
(d) Eye colour

Online Notes on Chapter = 9 ( Heredity and Evolution) Part 3

This is Online Notes on Chapter = 9 ( Heredity and Evolution)  Part 3 for
preparation of CBSE BOARD Examination, NTSE etc.





Evolution and Classification:

Both evolution and classification are interlinked =>

1. Classification of species is reflection of their evolutionary relationship.
2. The more characteristic two species have in common the more closely
they are related.
3. The more closely they are related, the more recently they have a common
ancestor.
4. Similarities among organisms allow us to group them together and to
     study their characteristic.

TRACING EVOLUTIONARY RELATIONSHIPS:

(Evidences of Evolution)

I. Homologous Organs: (Morphological and anatomical evidences). These
are the organs that have same basic structural plan and origin but different functions.

Homologous organs provides evidence for evolution by telling us that they
are derived from the same ancestor.

Evolution by Stages:

Evolution takes place in stages i.e., bit by bit generations.

I. Fitness Advantage:

Evolution of Eyes : Evolution of complex organs is not sudden. It occurs
due to minor changes in DNA, however takes place bit by bit over generations.

• Flat worm has rudimentary eyes. (Enough to give fitness advantage)
• Insects have compound eyes.
• Humans have binocular eyes.

II. Functional Advantage:
Evolution of Feathers : Feathers provide insulation in cold weather but later
they might become useful for flight.
Example, Dinosaurs had feathers, but could not fly using feathers. Birds
seem to have later adapted the feathers to flight.

Although there is great diversity of human forms all over the world, yet all
humans are a single species.

GENETIC FOOTPRINTS OF HUMANS:

Hundreds/thousand of years ago

• They did not go in a single line.
• They went forward and backward.
• Moved in and out of Africa.
• Sometimes came back to mix with each other.

Genetic Terminology:

1. Gene : Mendel used the term factor for a gene. A gene is the unit of
DNA responsible for the inheritance of character.

2. Allele : A pair of genes that control the two alternatives of the same
character e.g., TT/tt.

3. Heterozygous : The organism in which both the genes of a character are
unlike e.g., Tt.

4. Homozygous : The organism in which both the genes of a character are
similar e.g., TT, tt.

5. Dominant : The gene which expresses itself in F1 generation is known
as dominant gene.

6. Recessive : The gene which is unable to express itself in presence of the
dominant gene.

7. Genotype : It is the genetic constitution of an organism which determines
the characters.

8. Phenotype : It is the appearance of an individual.

9. Micro-evolution : It is the evolution which is on a small scale.

10. Species : A group of similar individuals within a population that can
interbreed and produce fertile offspring.

11. Chromosome : Thread like structures present in the nucleus of a cell,
containing hereditary information of the cell.

12. DNA : Deoxyribose Nucleic Acid.
It is present in chromosomes which carries traits in a coded form, from one
generation to the next.

Online Notes on Chapter=9 ( Heredity and Evolution) Part 2

This is Online Notes on Chapter=9 ( Heredity and Evolution)  Part 2 for preparation of CBSE BOARD Examination, NTSE etc.





Dihybrid Cross:
A cross between two plants having two pairs of contrasting characters is

called dihybrid cross.

Conclusion:
No genetic change has occurred in the population of beetle. The population
gets affected for a short duration only due to environmental changes.

ACQUIRED AND INHERITED TRAITS: