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Explanation

The statement that Cycas have vessel elements in their xylem is incorrect.

Cycas, like other gymnosperms, do not have vessel elements; instead, they have tracheids for water conduction.

Vessel elements are a characteristic of angiosperms (flowering plants).

Cycas are gymnosperms and produce seeds, but they do not form flowers, and their leaves are typically pinnately compound.

Explanation

Bryophytes are a group of non-vascular plants, which include mosses, liverworts, and hornworts.

They are characterized by their lack of vascular tissue (xylem and phloem) and reproduce via spores instead of seeds.

Explanation

The central atom of hemoglobin is iron, which binds to oxygen in the blood.

Hemoglobin is a protein in red blood cells responsible for transporting oxygen from the lungs to the rest of the body.

Explanation

Epistasis occurs when the expression of one gene is affected by another gene at a different locus.

This interaction can mask or modify the effects of the other gene, leading to variations in phenotypes.

Explanation

Gel electrophoresis is a technique used to separate DNA fragments based on their size by applying an electric field to a gel matrix.

Explanation

Promoter sites are specific DNA sequences where RNA polymerase binds to initiate transcription, the process of copying a gene's DNA sequence into RNA.

Explanation

Arachnids, such as spiders and scorpions, are distinguished by having eight legs, a characteristic feature of this class.

Explanation

The endosymbiont hypothesis suggests that mitochondria and chloroplasts originated as free-living bacteria that were engulfed by ancestral eukaryotic cells.

The presence of their own DNA and similarities with certain bacteria strongly support this hypothesis.

Explanation

The body wall of sponges is composed of two main layers: the pinacoderm and the choanoderm.

The pinacoderm is the outermost layer, made up of flat cells called pinacocytes, which cover the external surface of the sponge.

Explanation

اداس Gloomy

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