True or false? marijuana and hallucinogenic drugs produce psychological but not physical dependence.

How many variables are altered in a good experiment? a.1 b.0 c.2 d.3

Could someone me with number one you

In a classic experiment using pea shape, mendel conducted two separate genetic crosses. in the first cross the parent plants were “true breeding” for pea shape; one had round peas ( r )and the other had wrinkled (r). the first cross produced a filial 1 generation of all round peas. in the second cross, mendel bred plants from the filial 1 generation. this cross produced different results. out of approximately 1000 plants, about 75% were round and 25% were wrinkled.