The tissue whose cells are thin-walled and living, more or less isodiametric and have intercellular spaces, is known as

The correct answer is parenchyma

Key Points

Simple Permanent tissues: 

• The tissues which are specialized to offer elasticity, flexibility, and strength to the plant but have lost their ability to distribute. 
• Simple Permanent Tissue can be classified into the parenchyma, sclerenchyma, collenchyma, based on their purpose. 

Parenchyma: 

• These are living polygonal cells with a big central vacuole & intercellular spaces amidst them.
• Parenchymatous cells are responsible to create ground pith & tissue.
• It comprising of chloroplasts and that's why it is termed as chlorenchyma & it helps in photosynthesis.
• Parenchyma which comprises of The big air voids is called aerenchyma. 'Buoyancy' is the main purpose of aerenchyma.
• Some of these cells perform as storage chambers for starch in fruits & vegetables.

Additional Information

Collenchyma: 

• These have minute intercellular gaps & are stretched out living cells. 
• Their cell walls are made up of cellulose & pectin.
• Collenchyma is found in the marginal regions of stems & leaves.
• It offers mechanical support in plants & offers flexibility with the structural framework.

Sclerenchyma: 

• In their cell wall, these are dead cells with lignin deposits.
• Sclerenchyma is found in the covering of seeds and nuts, veins of leaves, and around the vascular tissues in stems. 
• It provides strength to the plant & they have no intercellular gaps.

Chlorenchyma

• Chlorenchyma is a type of parenchymatous tissue that contains chlorophyll and assists plants in performing their photosynthetic function.
• It can be found below the epidermis on the leaf stalks or in the mesophyll area of leaves.
• Some plants’ green stems may also contain it.