Rigid skeletons are formed from materials including chitin (in arthropods), calcium compounds such as calcium carbonate (in stony corals and mollusks) and silicate (for diatoms and radiolarians).
Answer:
Explanation:
Common insect adaptations include an exoskeleton (outer skeleton), camouflage, wings, the ability to have lots of babies, and adapted legs and mouthparts
Answer:
C
Explanation:
The meninges are the membranous tissues that cover the spinal cord and the brain, providing support and protection to these organs. They are of three layers.
A) The Dura mater
B) The arachnoid mater
C) The pia mater
The Dura is the outermost meningeal layer and lies directly under the vertebral column bones and skull. The subdural space is the space between the Dura mater and the Arachnoid mater.
The Arachnoid mater lies in the middle of the Dura and Pia mater. Under the Arachnoid layer is the subarachnoid space which contains the cerebrospinal fluid. The cerebrospinal fluid acts as a shock absorber and a cushion to the brain and spinal cord.
The Pia mater lies under the subarachnoid space and directly on the spinal cord and brain and is highly vascularised.
In the lac operon, glucose also plays an important role along with lactose. When Lactose is present in the environment along with glucose then it cannot deactivate the regulator gene [repressor], as a result, the repressor will bind to the operator and the transcription will be blocked.
When Lactose is present in the environment without glucose then the Catabolite repressor protein will bind to the CAP Site, and lactose will bind to the repressor [regulatory gene product], as a result, the repressor gets deactivated and the transcription takes place.
Lac operon: It is a set of three structural genes z, y, and a which are all transcribed and regulated under one single promoter. The three genes code for β-galactosidase, lactose permease, and transacetylase respectively.
β-galactosidase is responsible for breaking the lactose into glucose and galactose, lactose permease is responsible for transporting lactose across the cell membrane and transacetylase attaches a particular chemical group to target molecules.
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