NERVOUS SYSTEM EVOLUTION

Question 1

WHAT KIND OF NS DOES A SINGLE CELLED ORGANISM SUCH AS A EUGLENA

Answer 1

BASIC NS PROPERTIES
RESPONDS TO LIGHT PHOTONS TRANSDUCED BY PIGMENT LOCALISED TO AN EYE SPOT
HAS A FLAGELLUM TO PROPEL

Question 2

COME COMES WITH MULTICELLULARITY

Answer 2

SPECIALISATION

Question 3

WHAT DOES COMPLEXITY ALLOW

Answer 3

ANTICIPATORY AND RESPONSIVE BEHAVIOURS

Question 4

WHAT DOES THE NS OF A SPONGE ENTAIL

Answer 4

WATER FLOWS IN THROUGH THE BODY WALL
WATER FLOWS OUT VIA THE OSCULUM
FLOW REGULATED BY MYOCYTES SPECIALISED RESPONSE TO STRETCH

Question 5

IT IS THOUGHT THAT STRETCH RECEPTIVE MYOCYTES EVOLVED INTO THE PRIMORDIAL NS - HOW

Answer 5

MECHORECEPTIVE CELLS THAT SPAN THE OUTER EPITHELIAL ECTODERM LAYER EVOLVED INTO THE FIRST NEURONS: CELL THAT SPAN FROM THE EXTERIOR TO THE INTERIOR EFFECTOR CELLS
OVER TIME SOME NEURONS EVOLVED TO BE BENEATH THE OUTHER ECTODERM.

Question 6

A HYDRA IS THOUGHT TO HAVE SIMPLE NERVE NETS - WHAT NEW EVIDENCE IS THERE

Answer 6

HYDRA ALSO SECRETE REGULATORY PEPTIDES (HORMONES)

Question 7

WHAT FEATURES OF FLAT WORMS AND SEGMENTED WORMS SHOW FEATURES OF HIGHER ORGANISMS

Answer 7

1. GANGLIATION
2. CEPHALISATION
3. BILATERAL SYMMETRY
4. FASCICULATION
5. COMMISSURES

Question 8

IN HUMANS, WHY IS THE BASAL FOREBRAIN NEAR THE SOFT PALATE OF THE MOUTH

Answer 8

EVOLUTIONARILY IT IS MORE LIKELY THAT SURVIVAL WILL OCCUR IF YOU CAN FEED IN A CONTROLLED FORM.

Question 9

WHY IS THE C ELEGANS A GOOD MODEL ORGANISM

Answer 9

ITS NERVOUS SYSTEM HAS BEEN MAPPED
302 NEURONS
56 GLIA

Question 10

WHAT ARE THE NERVE CORDS OF THE C ELEGANS

Answer 10

VENTRAL, DORSAL AND LATERAL

Question 11

AS C ELEGANS DEVELOPS FROM A SINGLE CELL WE CAN TRACE THE PROGENY AS THEY DIVIDE AND DIFFERENTIATE. WHAT DOES P0 BECOME.

Answer 11

P1 - BODY, MUSCLES, GUT, SOMATIC GONADS, GERMLINE

AB - HYPODERMIS AND NS

Question 12

WHAT ARE THE STEPS OF THE DEVELOPING DROSOPHILA

Answer 12

1. THE NEUROGENIC REGION IS NEXT TO THE FUTURE SKIN
2. MIGRATION OF NEUROGENIC REGION DOWNWARDS
3. INVAGINATION OF MESODERM
4. NEUROGENESIS - MIGRATION INWARDS OF THE NEUROGENIC REGION INTO NEUROBLASTS

Question 13

WHAT IS THE KEY DIFFERENCE BETWEEN VERTEBRATES AND INVERTEBRATES

Answer 13

IN VERTEBRATES, THE NS ARISES FROM A SHEET OF CELLS CALLED THE NEURAL PLATE WHICH ROLLS UP TO FORM A TUBE EXTENDING THE AP AXIS
IN VERTEBRATES THE NS IS ON THE DORSAL SIDE