8.1-8.2 Reproduction

Question 1

Chromosomes

Answer 1

present in nucleus of a cell
contain DNA molecules (deoxyribo nucleic acid) that contains information concerning inheritance of features and protein production

Question 2

Are cells produced via reproduction identical?

Answer 2

No: no bio-chemical reaction is absolutely reliable, there will be variations each time

variations may be fatal or may be advantageous

Question 3

Why is consistency/variation imp?

Answer 3

A certain level of consistency in reproduction ensures the stability in the population of species

variations may be may be advantageous and help an organism survive despite changes in its niche

Question 4

Asexual modes 6

Answer 4

Fission
Spore formation
Regeneration
Vegetative propagation
Budding
Fragmentation

Question 5

Fission (cell division) in

Amoeba

Leishmania

Plasmodium

Yeast

Answer 5

Amoeba: splits into 2 equal halves, can divide on any plane

Leishmania: divides in a particular direction with respect to cellular structures

Plasmodium: multiple fission, reproduces multiple daughter cells simultaneously

Yeast: grows buds that separate and grow further

Question 6

Malarial parasite

Kala-azar causing microbe

Answer 6

Plasmodium

Leishmania

Question 7

Spirogyra (multi cellular) reproduction

Answer 7

Breaks into ‘fragments’ or smaller pieces upon maturation

These pieces grow into new organisms

Question 8

Why can’t all organisms use fragmentation to reproduce

Answer 8

Complex multi cellular organisms are not a random collection of cells.

They are organized into specialized tissues and organs that must exist in specific locations in the body.

Such an arrangement requires more complex ways of reproduction

Question 9

Regeneration definition

Why is it nor reproduction

Answer 9

The process by which a differentiated organism gives rise to a new organisms from their body parts (hydra, planaria)

Getting cut is a prerequisite for regeneration, which most organisms cannot rely on for reproduction

Question 10

Regeneration process

Answer 10

Specialised cells proliferate and make a large number of cells

From this mass, different cells undergo changes and transform into different specialized cells and tissues

These changes occur in an organized sequence reffered to as development

Question 11

Budding in hydra

Answer 11

A bud develops due to repeated cell division at a specific spot

These buds develop into separate individuals when mature and detach from the parent body

Question 12

vegetative propagation + example

Answer 12

process by which the roots, stems and leaves of certain plants, under appropriate conditions, develop into new plants

buds on leaf margin of bryophyllum

Question 13

vegetative propagation benefits

Answer 13

• used in layering/grafting to grow sugarcane/rose/grapes for agriculture
• can bear fruits and flowers earlier
• allows plants like jasmine, banana, rose, orange (which lost ability to produce seeds) to reproduce
• genetically similar enough to parent to share all characteristics
• fast

Question 14

Reproduction of rhizopus/ bread mould

Answer 14

fungus is composed of hyphae (thread like) which develop the sporangius

sporangia contain cells/spores that can develop into new rhizopus

spores are covered by thick walls that protect them until they come in contact with moist surface appropriate for growth