Answer and explanation:
1. A fluid of lymph and blood that circulates within invertebrates -- Hemolymph.
Hemolymph is a liquid, analog to blood, that is found in arthropods (invertebrates that have an exoskeleton, like insects and arachnids). Hemolymph has hemocyanin, which are proteins that transport oxygen, much like vertebrates' hemoglobin.
2. Protein cells that assist in fighting infection and disease - interferon.
Interferons are proteins released by host cells in the presence of several viruses. Interferons are a type of cytokine, which are molecules used to trigger the immune response. This way, they assist in fighting infections.
3. Type of leukocyte that makes up the specific immunity system; capable of building immunity to a disease - Lymphocyte.
Lymphocytes are one of the 5 types of leukocytes (white blood cells) present in the body. There are three types of lymphocytes: B (they mature in the bone marrow), T (they mature in the thymus), and NK -natural killers-. Lymphocytes participate in both the cell-mediated and the humoral responses of the immune system.
4. Excretory tubules in insects and spiders that empty into the intestine - Malpighian tubules.
The malpighian tubule system is found in insects, myriapods and arachnids, and is a type of excretory and osmoregulatory system that absorbs water and solutes from the hemolymph.
5. The functioning unit of Kidney that produces urine - Nephron.
The nephron is the functional unit of the kidney, composed of a renal corpuscle (which consists of a tuft of capillaries surrounded by the Bowman's capsule) and a renal tubule. There are over one million nephrons in the kidney. The function of the nephrons is to produce urine through blood filtration.
6. Tubes in flatworm and earthworms that excrete waste - Nephridia.
Nephridia are organs found in the invertebrates that are analog to the kidneys found in the vertebrates. Nephridia remove metabolic wastes from the invertebrates' bodies.
