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.
D.
Vascular cambium is not present.
The vascular system consists of complex tissues, the phloem and the xylem.
The xylem and phloem together constitute vascular bundles. In dicotyledonous stems, cambium is present between phloem and xylem. Such vascular bundles because of the presence of cambium possess the ability to form secondary xylem and phloem tissues, and hence are called open vascular bundles. In the monocotyledons, the vascular bundles have no cambium present in them. Hence, since they do not form secondary tissues so they are referred to as closed.
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.
Gametophyte and sporophyte are independent of each other in which of the following groups?
Pteridophytes
Angiosperms
Gymnosperms
Bryophytes
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
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
Which of the following is correct?
Paneth cells secrete pepsinogen
Parietal cells secrete hydrochloric acid
Argentaffin cells secrete mucus
Chief cells secrete gastrin
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 |
