Which of the following is correct about the given figure?
The length ofthe thick and thin myofilaments has changed.
Length of both anisotropic and isotropic band has changed.
The myosin cross-bridges move on the surface of actin and the thin and thick myofilaments slide past each other.
Length of the sarcomere remains same.
C.
The myosin cross-bridges move on the surface of actin and the thin and thick myofilaments slide past each other.
Myofibrils are composed of smaller structures called myofilaments. These are of two types: Thick filaments and Thin filaments.
1. Thick filaments- composed of myosin proteins, tails of which bind together leaving the heads exposed to the interlaced thin filaments.
2. Thin filaments- composed of actin, tropomyosin band troponin.
The molecular model of contraction which describes the interaction between actin and myosin myofilaments is called the cross- bridge cycle.
What is correct about the movement of substance across the membrane in facilitated diffusion?
It is an active transport
It doesn't cause transport of molecules from low concentration to high concentration
It is insensitive to inhibitors
It is a very specific transport
Refer the given figures on photoperiodism and select the correct option.
| A | B | C |
| no correlation between light period and flowering | long light- exposure period | short light- exposure period |
| A | B | C |
| long light- exposure period | no correlation between light period and flowering | short light- exposure period |
| A | B | C |
| short light exposure period | long light exposure period | no correlation between light period and flowering |
| A | B | C |
| no correlation between light period and flowering | short light exposure period | long light exposure period |
Which of the following is correct?
Paneth cells secrete pepsinogen
Parietal cells secrete hydrochloric acid
Argentaffin cells secrete mucus
Chief cells secrete gastrin
Why are vascular bundles closed in monocots?
Xylem and phloem are present.
Xylem and phloem occur in separate bundles.
Vascular cambium is present between xylem and phloem.
Vascular cambium is not present.
What do A, B, C and D represent in the following figure?
A : carrier protein, B: symport, C: uniport, D : antiport
A : carrier protein, B : uniport, C: antiport, D : symport
A: carrier protein, B: antiport, C: symport, D : uniport
A : carrier protein, B: uniport, C: symport, D : antiport
Gametophyte and sporophyte are independent of each other in which of the following groups?
Pteridophytes
Angiosperms
Gymnosperms
Bryophytes
