<h3><u>Benefits of smooth stem  over rough stem:</u></h3>
Smooth stem plants like guava, eucalyptus etc do have a smooth layer of bark over its stem that comes out as a skin when they shed their barks. Whereas most of the other plants like mango, banyan etc do have a rough corrugated layer of bark over their stem. 
The smooth stem doesn’t let water to accumulate in the bark which can led to infections to the tree. It also doesn’t allow any seed to settle on bark that can led to growth of parasites. Thereby this smooth bark saves the trees from some of the probable harm to the tree.  
 
        
        
        
Answer:
The correct answer is "1. cornea 2. retina 3. rods and cones 4. ganglion cells
5. optic nerve 6. thalamus 7. primary visual cortex"
Explanation:
Light must pass a series of structures for the brain being able to interpret the data that comes from the eyes. The order that light stimuli travels from the eye to the brain is as follows:
1. cornea
2. retina
3. rods and cones
4. ganglion cells
5. optic nerve
6. thalamus
7. primary visual cortex
Light enters trough the cornea, the transparent front part of the eye that covers two-thirds of its total optical power; then it goes to the retina which receives the image that could go to the rods or the cones (depending if the light is at low or high levels, respectively). Then, ganglion cells increase the rate of the impulse within the optic nerve, and finally thalamus passes the sensory signal to the primary visual cortex. In this area of the brain, the basic visual features are extracted and interpreted.