A signaling molecule binding with a receptor molecule is like... A: the refrigerator in a house

B: a door in a house

C: the walls of a house

D: a key fitting into a lock

D

Explanation:

You are binding a key into a lock to make it open

relationships aren't everything. people everyday spend there entire life depending on reltionships and for someone to be there for them when this is absurd. why must people depend on someone else to bring them happiness? i'm not saying it wrong to feel happy with someone, but people feel that they need to be in a relationship in order to feel happy, when, this is not true. you can paint, write, read ir slend tume with family ir even spend time working in yourself. this can be an exciting experience to find yourself. it's bot wrong to be in a relationship but if you let it be your only source of happiness, than you will never find true happiness.

so, relationships are not always worth it. if you are so dependent on them, than in the end they arent worth it because you will realize how unhappy you really were. some people even tend to cut ties with family because they think they cabt make them happy, obly realtionships with a lover can. false. in order to find true happiness, one must learn to love themselves if they want to love someone else. it's unhealthy to be always depend on relationships and to alqays be in and out of one.

so live life, get that job you always wanted, buy those new shoes and love yourself. depend on yourself, not others. they arent worth it, you can make yourself more happier than most people can do to you. it's not woth it. take your time and have fun.