Test: Hydra - 2 (Old NCERT) - NEET MCQ

In Hydra, musculo-nutritive cells are present which is large, columnar, nucleated and vacuolated. The free ends of the cells project into coelenteron which bear pseudopodia and one to five flagella. With the help of pseudopodia and flagella, the cells engulf food material (holozoic ingestion).

Asexual reproduction produces individuals that are genetically identical to the parent plant. Roots such as corms, stem tubers, rhizomes, and stolon undergo vegetative reproduction. Some plants can produce seeds without fertilization via apomixis where the ovule or ovary gives rise to new seeds.

Hydra (phylum: Cnidaria) body wall consists of outer epidermis and inner gastrodermis separated by acellular mesoglea. Epitheliomuscular cells are present in the epidermis and serve in protection and shortening of body and tentacles by contraction. A diffuse network of nerve cells in epidermis makes nerve net that serves to conduct impulses in all directions and helps Hydra (cnidarians) to respond. Cnidocyte is the stinging cells present in the epidermis of Hydra and serve in protection and catching the prey. Choanocytes, the flagellated collar cells are the characteristic feature of phylum Porifera and serve in setting the water current that delivers food and oxygen and removes waste and carbon dioxide.
So, the correct answer is option D.

Hydra is primite so as it have diffuse nervous system and diffuse nervous system is a primitive system. In diffuse systems nerve cells are distributed throughout the organism, usually beneath the outer epidermal layer that is why it's impulse transmission is in all directions.

When a hydra is well fed in abundance of CO₂, a new bud can form every two days. In harsh conditions Sexual reproduction occurs in some Hydra. Swellings in the body wall develop into either ovaries or testes. The testes release free-swimming gametes into the water, and these can fertilize the egg in the ovary of another individual.

When not so attached it is helpless, for it has not the power of swimming. When attached the body is usually moderately expanded, seldom extremely so. In Hydra viridis the tentacles, also moderately expanded, extend obliquely outward and forward, forming the framework of a sort of funnel with the hypostome at the bottom. If dettaches causing the hydra to float upside- down as the base detaches, no food catchment, etc

Cnidarian animals are characterised with cnidoblasts or cnidocytes (which contain the stinging capsules or nematocysts) present on the tentacles and the body. Cnidoblasts are used for anchorage, defense and for the capture of prey. Nematoblasts of cnidoblasts are sensory in nature and they contain nematocyst apparatus.
Therefore, the correct answer is option C.

Hydra can digest proteins, fats, and some carbohydrates, but it does not digest starch because they lack salivary amylase and pancreatic amylase.
So, the correct answer is 'Starch'.

Hydra belongs to cnidarians which are radially symmetrical and diploblastic acoelomate.

In cnidarians, the cell can use its thread and nematocyst only once. Later the used cell is replaced by newly generated cnidoblast cell.

Blind sac is a characteristic of Hydra. The body has a cavity or is like a sac with only one opening. The digestive tract is, therefore, incomplete in this type of body plan. They have diploblastic body plan with two germ layer which is known as ectoderm and endoderm.
Therefore, the correct answer is option B.

In Hydra, undigested residues are egested from coelenteron through the mouth, while nitrogenous excretory product (ammonia) is removed from the general body surface. They lack any organ level organisation, they have a tissue level organisation. They have a gastrovascular cavity which helps in digestion and absorption. 

So, the correct answer is option C.

Hydra which belongs to the phylum coelenterata has nerve cells but no brain. Its nervous system consists of nerve cells and their processes. Sensory cells are also present. Sponges do not have nerve cells, they lack nervous system. Earthworm (annelida) has nervous system consisting of a circumenteric nerve ring and a solid, double, midventral nerve cord with ganglia. Cockroach (arthropoda) has the nervous system as that of earthworm.
So, the correct answer is 'Hydra'.

Because hydra reproduces vegetatively through a process called budding. In budding, each bud grows into a new individual and hence, all the cut three parts grows into a new individual.

Buds are produced every two to three days under favourable conditions. Buds later break free, but are genetically identical to the parents (clones). Under favorable conditions, hydra may possess several buds at various stages of development. Hydras often have four buds at a time.