Read Passage 1.

The dog laugh sounds similar to a normal pant. But by analyzing the pant using a sonograph, this pant varies with bursts of frequencies, resulting in a laugh. When this recorded dog-laugh vocalization is played to dogs in a shelter setting, it can initiate play, promote pro-social behavior, and decrease stress levels. In a study by Simonet, Versteeg, and Storie, 120 subject dogs in a mid-size county animal shelter were observed. Dogs ranging from 4 months to 10 years of age were compared with and without exposure to a dog-laugh recording. The stress behaviors measured included panting, growling, salivating, pacing, barking, cowering, lunging, play-bows, sitting, orienting and lying down. The study resulted in positive findings when exposed to the dog laughing: significantly reduced stress behaviors, increased tail wagging and the display of a play-face when playing was initiated, and the increase of pro-social behavior such as approaching and lip licking were more frequent. This research suggests exposure to dog-laugh vocalizations can calm the dogs and possibly increase shelter adoptions.

The word pant here means

Read Passage 2.

Men and women take jokes differently. A study that appeared in Proceedings of the National Academy of Sciences found in a study, 10 men and 10 women all watched 10 cartoons, rating them funny or not funny and if funny, how funny on a scale of 1–10. While doing this, their brains were scanned by functional magnetic resonance imaging (fMRI). Men and women for the most part agreed which cartoons were funny. However, their brains handled humor differently. Women’s brains showed more activity in certain areas, including the nucleus accumbens. When women viewed cartoons they did not find humorous, their nucleus accumbens had a “ho-hum response.” A man's nucleus accumbens did not react to funny cartoons, and its natural activity level dropped during unfunny cartoons.

The word nucleus accumben here means

Read Passage 3.

Courses with the numbers 800 or above are open only to introductory material, are numbered 400 for undergraduate students and 600 for graduate students. Courses designed for students seeking a professional degree carry a 500 number for undergraduate students and a 700 number for graduate students. A full-time graduate student is expected to take courses which total ten to sixteen credit hours. Students holding assistantships are expected to enroll for proportionately fewer hours. A part-time graduate student must register for a minimum of five credit hours.

The word number here means

Read Passage 4.

Although nearly five hundred species of Acacia have been identified, only about a dozen of the three hundred Australian varieties grow well in the southern United States, and of these, only three are flowering. The Bailey Acacia has fernlike silver leaves and small, fragrant flowers arranged in rounded clusters. The Silver Wattle, although very similar to the Bailey Acacia, grows twice as high. The Sydney Golden Wattle is squat and bushy with broad, flat leaves. Another variety, the Black Acacia or Blackwood, has dark green leaves and unobtrusive blossoms. Besides being a popular tree for ornamental purposes, the Black Acacia is valuable for its dark wood which is used in making cabinets and furniture.

The word unobtrusive here means