Why do living things use enzymes instead of heat as a source of activation energy? o adding sufficient heat would harm or kill a living thing. o adding heat would not give the reactants enough energy. o adding heat gives reactants the wrong kind of energy. o adding heat does not affect how chemical reactions take place.

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.

answer///multiple alleles;

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.