Support and Movement

which of the following graphs represents the relationship between cutin layer thickness and environmental conditions ( raIinfall and drought)

• a

• b

• c

• none

Read the statement regarding myofibril and choose the correct option :

1- Each myofibril halined alternate dark and light bands.

2-In the center of each A band is an elastic fiber called Z-line

3- A and I are arranged alternately through out the length of myofibril.

4- The sarcomere is the functional unit of contraction

5- The central part of thick filament not overlapped by a thin filament is M line

• 1,3,5 only are correct

• 2,5 only are correct

• 2,3 are only correct

• 1,3,4 are only correct

In the diagram , where would you find the stored Ca+2?

• B

• D

• G

• F

• K

In the diagram , sarcolemma is represented by

• K

• I

• L

• M

• A

In the diagram, sarcoplasm is represented by

• K

• C

• L

• D

• E

In the diagram, myofibril is represented by

• I

• A

• H

• J

• M

Statement (A) Calcium activates inter effect of actin and myosin

Reason (R) Sarcomere is shortened as Z is pulled in slide , attached with myosin

• Both A and R are true and R is correct explanation of A

• Both A and R are true but R is not correct explanation of A

• A is true but R is false

• A is true but R is true

Neurotransmitter released from motor nerve terminals sets off a sequence of events that ultimately results in contraction of skeletal muscle .Arrange in the correct order the events that occur when neurotransmitter is released:

1- depolarization of sarcolemma

2- binding of Ca+2 to troponin

3- Depolarization of T tubules

4-Shift in the tropomyosin position to expose myosin- binding sites on actin

5- Release of Ca+2 from the sarcoplasmic reticulum

6-repeated binding and release of myosin to actin

• 1.2.3.4.5.6

• 1.3.5.4.2.6

• 1.53.2.4.6

• 1.3.5.2.4.6

• 1.2.4.3.5.65

The following graph represents the results of studying a scientist for the effect of increasing the concentration of auxins on the plant cell.

what could be deduced from studying the graph?

• Increasing in auxins concentration leads to increasing in cells growth to a certain limit

• Auxins have no effect on cells growth

• Increasing auxins concentration leads to continous growth of cells

• The rate of cell division decreases by decreasing auxins concentration

T he blossming of the four o'clock flower is an example of

• phototropism

• photonasity

• thermotropism

• thermonasty