Biology today

Table : Differences between Prototheria, Metatheria and Eutheria

Prototheria Theria

Metatheria Eutheria

1. • Ear without pinna. • Ear with pinna. • Ear usually with pinna.


2. • No nipples (mammae). • Nipples abdominal. • Nipples abdominal or thoracic.


3. • No corpus callosum. • Corpus callosum feebly developed
   or absent.

•    Corpus callosum present.

4. • Testes abdominal, no scrotum. • Scrotum in front of penis. • Scrotum behind penis.


5. • Digestive and urinogenital tracts
   open out through cloaca and
   cloacal aperture.

•    Digestive and urinogenital tracts

open out by separate apertures

that are controlled by a common

sphincter muscle.

•    Digestive and urinogenital tracts

open out by separate apertures,

each with its own sphincter

muscle.

6. • No marsupial pouch. • Marsupial pouch often present. • No marsupial pouch.


7. • Oviparous. • Viviparous. • Viviparous.


8. • No placenta. • Placenta small, intrauterine
   development brief, young
   extremely small and helpless,
   brought up in marsupial pouch, if
   present.

•    Placenta large, intrauterine

development prolonged, young

advanced and fully formed.

9. • Examples : Duck-billed platypus
   (Ornithorhynchus anatinus), Spiny
   anteater (Tachyglossus )

•    Examples : Kangaroo (Macropus),

Opossum (Didelphis).

•    Examples : Rat (Rattus),

Horse (Equus).

1. Describe briefly how mammals have originated.


2. What are the physiological adaptations that helped mammals to be successful?

• He recognised 18 living and 14 extinct orders of
mammals. For the purpose of this text, we shall refer to
only 18 living orders of mammals which were first divided

into 2 subclasses: Prototheria and Theria. Theria were

further divided into 2 infraclasses: Metatheria and

Eutheria.

C : Citric acid

C : Cis aconitic acid

I : Isocitric acid

o : Oxalosuccinic acid

K : a-Ketoglutaric acid

S : Succinyl CoA

S : Succinic acid

F : Fumaric acid

M : Malic acid

O : Oxaloacetic acid

To easily remember the stepwise components of ten stepped

Krebs cycle, the mnemonic “Cricket Club India Often Keeps Smart

Secretary For Main Officer” can be used as follows:

MgiMS : 17 th April

kerala PMT : 27 th & 28th April

AiPMT : 1 st May

wbjEE : 17 th May

AiiMS : 29 th May

EXAM DATES 2016